Add Twitter and LinkedIn publishers with Playwright sidecars

- Create twitter-post sidecar with Playwright for browser automation
- Create linkedin-post sidecar with Playwright for browser automation
- Add TwitterPublisher class that calls twitter-post sidecar
- Add LinkedInPublisher class that calls linkedin-post sidecar
- Register both publishers in PublisherManager via AppServiceProvider
- Update Posts index view to show Publish button for twitter/linkedin types

Both publishers use the same pattern as RedditPublisher:
- No API keys required (uses stored credentials from Social Accounts)
- Browser automation via Playwright
- Returns JSON result with success/failure and URL

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

sidecars/linkedin-post/.gitignore

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+/node_modules
+/test-results
+/.env

sidecars/linkedin-post/README.md

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+# LinkedIn Post Sidecar
+
+A Playwright acceptance test that logs into LinkedIn with supplied credentials and creates a post.
+
+## One-time setup
+
+    cd sidecars/linkedin-post
+    npm install
+    npx playwright install chromium
+
+## Usage
+
+    ./run.sh --email=YOUR_EMAIL --password=YOUR_PASSWORD \
+      --post="Your post content here" [--headed]
+
+Prints a single JSON line to stdout and exits 0 on success, exits 1 on failure:
+
+    {"success": true, "url": "https://www.linkedin.com/posts/..."}
+    {"success": false, "error": "Login failed: Invalid credentials"}
+
+## Notes
+
+- On a failed run, Playwright retains a screenshot and trace under `test-results/` for debugging.
+  These are gitignored and not committed, but they persist on disk.
+- LinkedIn's UI changes periodically. If posting fails, check the selectors in `tests/linkedin-post.spec.js`
+  and update them using: `npx playwright codegen https://www.linkedin.com/login`
+- LinkedIn may show CAPTCHAs or 2FA prompts which will cause the automation to fail.
+- For company pages, you may need to switch to the page after login before posting.

sidecars/linkedin-post/package.json

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+{
+  "name": "linkedin-post-sidecar",
+  "private": true,
+  "version": "1.0.0",
+  "description": "Playwright acceptance test that logs into LinkedIn and creates a post, invoked via run.sh",
+  "scripts": {
+    "test": "playwright test"
+  },
+  "devDependencies": {
+    "@playwright/test": "^1.61.1"
+  }
+}

sidecars/linkedin-post/playwright.config.js

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+/** @type {import('@playwright/test').PlaywrightTestConfig} */
+const config = {
+  testDir: './tests',
+  fullyParallel: false,
+  workers: 1,
+  reporter: 'json',
+  use: {
+    trace: 'retain-on-failure',
+    screenshot: 'only-on-failure',
+    video: 'retain-on-failure',
+  },
+};
+
+export default config;

sidecars/linkedin-post/run.sh

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+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR"
+
+EMAIL=""
+PASSWORD=""
+POST_TEXT=""
+HEADLESS_FLAG="true"
+
+for arg in "$@"; do
+  case "$arg" in
+    --email=*) EMAIL="${arg#*=}" ;;
+    --password=*) PASSWORD="${arg#*=}" ;;
+    --post=*) POST_TEXT="${arg#*=}" ;;
+    --headed) HEADLESS_FLAG="false" ;;
+    *)
+      UNKNOWN_FLAG="${arg%%=*}"
+      echo "{\"success\": false, \"error\": \"Unknown argument: $UNKNOWN_FLAG\"}"
+      exit 1
+      ;;
+  esac
+done
+
+MISSING=""
+[ -z "$EMAIL" ] && MISSING="$MISSING --email"
+[ -z "$PASSWORD" ] && MISSING="$MISSING --password"
+[ -z "$POST_TEXT" ] && MISSING="$MISSING --post"
+
+if [ -n "$MISSING" ]; then
+  echo "{\"success\": false, \"error\": \"Missing required argument(s):$MISSING\"}"
+  exit 1
+fi
+
+export LINKEDIN_EMAIL="$EMAIL"
+export LINKEDIN_PASSWORD="$PASSWORD"
+export POST_CONTENT="$POST_TEXT"
+export HEADLESS="$HEADLESS_FLAG"
+
+set +e
+npx playwright test tests/linkedin-post.spec.js
+PLAYWRIGHT_EXIT_CODE=$?
+set -e
+
+RESULT_FILE="test-results/result.json"
+
+if [ -f "$RESULT_FILE" ]; then
+  cat "$RESULT_FILE"
+  echo
+else
+  echo "{\"success\": false, \"error\": \"Test did not produce a result file\"}"
+  exit 1
+fi
+
+exit "$PLAYWRIGHT_EXIT_CODE"

sidecars/linkedin-post/tests/linkedin-post.spec.js

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+// @ts-check
+const { test, expect } = require('@playwright/test');
+const fs = require('fs');
+const path = require('path');
+
+const RESULT_PATH = path.join(__dirname, '..', 'test-results', 'result.json');
+
+function writeResult(result) {
+  fs.mkdirSync(path.dirname(RESULT_PATH), { recursive: true });
+  fs.writeFileSync(RESULT_PATH, JSON.stringify(result));
+}
+
+test.describe('linkedin post', () => {
+  let outcome = { success: false, error: 'Test did not complete' };
+  let outcomeFinalized = false;
+
+  test.afterEach(async () => {
+    writeResult(outcome);
+  });
+
+  test('logs into LinkedIn and creates a post', async ({ page }) => {
+    const email = process.env.LINKEDIN_EMAIL;
+    const password = process.env.LINKEDIN_PASSWORD;
+    const postContent = process.env.POST_CONTENT;
+
+    for (const [name, value] of Object.entries({
+      LINKEDIN_EMAIL: email,
+      LINKEDIN_PASSWORD: password,
+      POST_CONTENT: postContent,
+    })) {
+      if (!value) {
+        outcome = { success: false, error: `Missing required environment variable: ${name}` };
+        outcomeFinalized = true;
+        throw new Error(outcome.error);
+      }
+    }
+
+    try {
+      await page.goto('https://www.linkedin.com/login');
+
+      // Wait for page to load
+      await page.waitForLoadState('networkidle');
+
+      // Check for login form
+      const emailField = page.getByLabel(/email|phone/i).first();
+      if (!await emailField.isVisible({ timeout: 10000 }).catch(() => false)) {
+        outcome = {
+          success: false,
+          error: 'LinkedIn login form not found — page structure may have changed',
+        };
+        outcomeFinalized = true;
+        throw new Error(outcome.error);
+      }
+
+      // Fill email
+      await emailField.fill(email);
+
+      // Fill password
+      const passwordField = page.getByLabel(/password/i).first();
+      if (await passwordField.isVisible({ timeout: 10000 }).catch(() => false)) {
+        await passwordField.fill(password);
+      }
+
+      // Click sign in button
+      const signInButton = page.getByRole('button', { name: /sign in|signin|log in/i, exact: false }).first();
+      await signInButton.click();
+
+      // Wait for login to complete - check for feed or start post button
+      try {
+        await page.waitForURL('https://www.linkedin.com/feed/', { timeout: 20000 });
+      } catch {
+        // Check if we're logged in by looking for start post button
+        const startPostButton = page.getByRole('button', { name: /start a post|post/i, exact: false }).first();
+        if (!await startPostButton.isVisible({ timeout: 10000 }).catch(() => false)) {
+          const errorText = await page.textContent('body').catch(() => '');
+          outcome = {
+            success: false,
+            error: errorText.toLowerCase().includes('invalid') || errorText.toLowerCase().includes('incorrect')
+              ? 'Invalid LinkedIn credentials'
+              : 'LinkedIn login did not complete — possible CAPTCHA, 2FA, or invalid credentials',
+          };
+          outcomeFinalized = true;
+          throw new Error(outcome.error);
+        }
+      }
+
+      // Click "Start a post" button
+      const startPostButton = page.getByRole('button', { name: /start a post|post/i, exact: false }).first();
+      await startPostButton.click();
+
+      // Wait for post composer
+      const postTextarea = page.getByRole('textbox', { name: /what do you want to talk about/i, exact: false }).first();
+      if (!await postTextarea.isVisible({ timeout: 10000 }).catch(() => false)) {
+        // Try alternative selector
+        const altTextarea = page.locator('div[contenteditable="true"]').first();
+        if (await altTextarea.isVisible({ timeout: 5000 }).catch(() => false)) {
+          await altTextarea.click();
+          await page.keyboard.type(postContent);
+        } else {
+          outcome = {
+            success: false,
+            error: 'LinkedIn post composer not found — UI may have changed',
+          };
+          outcomeFinalized = true;
+          throw new Error(outcome.error);
+        }
+      } else {
+        await postTextarea.fill(postContent);
+      }
+
+      // Click post button
+      const postButton = page.getByRole('button', { name: /^post$/i, exact: true }).first();
+      if (await postButton.isVisible({ timeout: 5000 }).catch(() => false)) {
+        await postButton.click();
+      } else {
+        // Try alternative post button selectors
+        const altPostButton = page.getByRole('button', { name: /share|post/i, exact: false }).nth(1);
+        if (await altPostButton.isVisible({ timeout: 5000 }).catch(() => false)) {
+          await altPostButton.click();
+        }
+      }
+
+      // Wait for post to be created
+      await page.waitForTimeout(3000);
+
+      // Get current URL (should be the post URL or feed)
+      outcome = { success: true, url: page.url() };
+      outcomeFinalized = true;
+      expect(outcome.success).toBe(true);
+    } catch (err) {
+      if (!outcomeFinalized) {
+        outcome = { success: false, error: err instanceof Error ? err.message : String(err) };
+      }
+      throw err;
+    }
+  });
+});