Add favorite toggle to yoga poses

Exercises and workouts both have a favorite toggle; yoga poses had an
otherwise identical browse/filter UX but no way to favorite them - an
inconsistency rather than a deliberate omission. Mirrors the existing
exercise/workout favorite pattern exactly: a pivot table, a
belongsToMany on User, and a toggle button on the pose detail page.

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

database/migrations/2026_08_10_090234_create_yoga_pose_favorites_table.php

@@ -0,0 +1,30 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::create('yoga_pose_favorites', function (Blueprint $table) {
+            $table->id();
+            $table->foreignId('user_id')->constrained()->cascadeOnDelete();
+            $table->foreignId('yoga_pose_id')->constrained('yoga_poses')->cascadeOnDelete();
+            $table->timestamps();
+            $table->unique(['user_id', 'yoga_pose_id']);
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('yoga_pose_favorites');
+    }
+};