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>

.env.docker

@@ -0,0 +1,65 @@
+# ──────────────────────────────────────────────────────────────────────────────
+# eCert MBIP — Contoh .env untuk Docker
+# Salin ke .env dan ubah nilai yang perlu:
+#   cp .env.docker .env
+# ──────────────────────────────────────────────────────────────────────────────
+
+APP_NAME="eCert MBIP"
+APP_ENV=local
+APP_KEY=
+APP_DEBUG=true
+# PENTING: Tukar ke domain sebenar untuk production
+# Contoh: APP_URL=https://ecert.mbip.gov.my
+APP_URL=http://localhost:8003
+
+APP_LOCALE=ms
+APP_FALLBACK_LOCALE=ms
+APP_FAKER_LOCALE=ms_MY
+
+APP_MAINTENANCE_DRIVER=file
+
+BCRYPT_ROUNDS=12
+
+LOG_CHANNEL=stack
+LOG_STACK=single
+LOG_DEPRECATIONS_CHANNEL=null
+# Production: guna level "warning" atau "error"
+LOG_LEVEL=debug
+
+# ── Database ──────────────────────────────────────────────────────────────────
+DB_CONNECTION=mysql
+DB_HOST=db                # nama service dalam docker-compose.yml
+DB_PORT=3306
+DB_DATABASE=ecert_mbip
+DB_USERNAME=ecert
+# Tukar password ini!
+DB_PASSWORD=ecert_secret_2025
+
+# ── Session ───────────────────────────────────────────────────────────────────
+SESSION_DRIVER=database
+SESSION_LIFETIME=120
+SESSION_ENCRYPT=false
+SESSION_PATH=/
+SESSION_DOMAIN=null
+
+# ── Cache & Queue (guna database — tiada Redis diperlukan) ────────────────────
+BROADCAST_CONNECTION=log
+FILESYSTEM_DISK=local
+QUEUE_CONNECTION=database
+CACHE_STORE=database
+
+# ── Mail ──────────────────────────────────────────────────────────────────────
+# Dev: guna "log" untuk lihat email dalam storage/logs/laravel.log
+# Production: tukar ke SMTP
+MAIL_MAILER=log
+MAIL_SCHEME=null
+MAIL_HOST=smtp.mbip.gov.my
+MAIL_PORT=587
+MAIL_USERNAME=null
+MAIL_PASSWORD=null
+MAIL_ENCRYPTION=tls
+MAIL_FROM_ADDRESS="ecert@mbip.gov.my"
+MAIL_FROM_NAME="eCert MBIP"
+
+# ── Vite ──────────────────────────────────────────────────────────────────────
+VITE_APP_NAME="${APP_NAME}"