Add script/TTS step handlers, dashboard, and pipeline UI (#35, #36, #43, #44)

StepHandler abstraction (app/Support/VideoWorkflow/StepHandlers/) plugs
into WorkflowEngine without coupling it to how any given step type is
actually executed:
- ScriptGenerationHandler: builds a prompt from the project's title/
  description (or an explicit outline/tone/keywords/target length in
  step input), generates via an active OpenAI AiProvider, stores the
  result as a 'script' asset.
- TtsVoiceoverHandler: voices step.input.text, or falls back to the
  project's latest script asset, via an active ElevenLabs AiProvider;
  voice_id/model_id are configurable per step. No direct "speed"
  control — ElevenLabs' base TTS endpoint doesn't expose one.

RunWorkflowStepJob resolves a step's handler by type and runs it on
the queue, matching the existing PublishPostJob pattern (including a
stale-dispatch guard: no-op if the step isn't 'in_progress' anymore).

UI, under its own /video-projects routes and nav entry — separate
from /projects per the earlier decision:
- VideoProjects/Index (#43): list projects with status and step
  progress, create new ones.
- VideoProjects/Show (#44): start a project from a WorkflowTemplate or
  a hardcoded default 8-step pipeline; per-step Run/Approve/Reject/
  Retry/Skip actions; auto-queues the next step after any transition
  when a handler exists for its type (steps with no handler yet just
  sit in_progress rather than auto-failing); lists project assets.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/Feature/Livewire/VideoProjectsIndexTest.php

@@ -0,0 +1,54 @@
+<?php
+
+use App\Livewire\VideoProjects\Index;
+use App\Models\User;
+use App\Models\VideoProject;
+use App\Support\VideoWorkflow\WorkflowEngine;
+use Livewire\Livewire;
+
+test('video projects index page lists existing projects', function () {
+    VideoProject::factory()->create(['title' => 'My Awesome Video']);
+
+    $this->actingAs(User::factory()->create())
+        ->get(route('video-projects.index'))
+        ->assertOk()
+        ->assertSee('My Awesome Video');
+});
+
+test('a new video project can be created', function () {
+    Livewire::test(Index::class)
+        ->set('title', 'New Video')
+        ->set('description', 'A description')
+        ->call('save');
+
+    expect(VideoProject::where('title', 'New Video')->exists())->toBeTrue();
+});
+
+test('title is required to create a video project', function () {
+    Livewire::test(Index::class)
+        ->set('title', '')
+        ->call('save')
+        ->assertHasErrors(['title']);
+});
+
+test('a video project can be deleted', function () {
+    $project = VideoProject::factory()->create();
+
+    Livewire::test(Index::class)->call('delete', $project->id);
+
+    expect(VideoProject::find($project->id))->toBeNull();
+});
+
+test('it shows step progress counts for a started project', function () {
+    $project = VideoProject::factory()->create(['title' => 'Progress Test']);
+    $engine = new WorkflowEngine;
+    $step = $engine->start($project, [
+        ['type' => 'script_generation'],
+        ['type' => 'tts_voiceover'],
+    ]);
+    $engine->completeStep($step);
+
+    $this->actingAs(User::factory()->create())
+        ->get(route('video-projects.index'))
+        ->assertSee('1 / 2');
+});