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.ini

@@ -0,0 +1,44 @@
+; ──────────────────────────────────────────────────────────────────────────────
+; eCert MBIP — PHP Runtime Configuration
+; Letakkan dalam /usr/local/etc/php/conf.d/99-ecert.ini
+; ──────────────────────────────────────────────────────────────────────────────
+
+; Timezone Malaysia
+date.timezone = Asia/Kuala_Lumpur
+
+; ── Upload (template sijil hingga 10MB + buffer) ──────────────────────────────
+upload_max_filesize = 20M
+post_max_size       = 25M
+max_file_uploads    = 10
+
+; ── Execution (image generation + queue workers) ──────────────────────────────
+max_execution_time = 120
+max_input_time     = 120
+
+; ── Memory (Intervention Image untuk sijil resolusi tinggi) ───────────────────
+memory_limit = 512M
+
+; ── Session ───────────────────────────────────────────────────────────────────
+session.cookie_httponly = 1
+session.cookie_samesite = Lax
+session.gc_maxlifetime  = 7200
+
+; ── OPcache ───────────────────────────────────────────────────────────────────
+opcache.enable                = 1
+opcache.memory_consumption    = 192
+opcache.interned_strings_buffer = 16
+opcache.max_accelerated_files = 10000
+; validate_timestamps: 1 untuk dev (auto-reload), 0 untuk prod (prestasi)
+opcache.validate_timestamps   = 1
+opcache.revalidate_freq       = 2
+opcache.fast_shutdown         = 1
+
+; ── Error (override per environment via APP_ENV) ──────────────────────────────
+display_errors       = Off
+display_startup_errors = Off
+log_errors           = On
+error_log            = /var/log/php_errors.log
+
+; ── imagick ───────────────────────────────────────────────────────────────────
+[imagick]
+imagick.skip_version_check = 1