feat: Docker Compose setup untuk development & production

- docker/php/Dockerfile: PHP 8.4-FPM + GD + imagick (PECL) + semua extension Laravel
- docker/php/php.ini: upload 20MB, memory 512MB, opcache, Asia/Kuala_Lumpur
- docker/php/php-dev.ini: validate_timestamps=1, display_errors=On (dev)
- docker/nginx/default.conf: gzip, security headers, static asset caching
- docker/entrypoint.sh: tunggu MySQL → migrate → seed AdminSeeder → cache (prod)
- docker-compose.yml: dev stack — port 8003, DB host 33060, queue worker
- docker-compose.prod.yml: production overrides — storage volume, no DB port exposed
- .env.docker: template env untuk Docker (DB_HOST=db)
- .dockerignore: exclude node_modules, vendor, .env, logs

fix: testGenerate try/catch kembalikan JSON error (bukan HTML 500)
fix: loadPreview() semak r.ok, tunjuk error alert, loading spinner

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker/php/php-dev.ini

@@ -0,0 +1,13 @@
+; ──────────────────────────────────────────────────────────────────────────────
+; Development overrides — dilengkap di atas php.ini
+; Hanya dimuat dalam docker-compose.yml (dev), tidak dalam prod
+; ──────────────────────────────────────────────────────────────────────────────
+
+; Reload fail PHP tanpa restart container
+opcache.validate_timestamps = 1
+opcache.revalidate_freq     = 0
+
+; Tunjuk ralat dalam browser semasa dev
+display_errors         = On
+display_startup_errors = On
+error_reporting        = E_ALL