refactor: move supabase config to repo root, fix port and env setup

- Move supabase/ from packages/db/ to repo root for simpler CLI usage
- Use custom ports (553xx) to avoid conflicts with other local Supabase instances
- Add --env-mode=loose to turbo dev so root .env vars reach Next.js
- Remove hardcoded --port 3000 from next dev (reads PORT env var instead)
- Add .env.example with Supabase env var placeholders
- Add supabase local state dirs to .gitignore

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/db/package.json

@@ -2,6 +2,12 @@
   "name": "@pascal-app/db",
   "version": "0.0.0",
   "type": "module",
+  "scripts": {
+    "db:generate": "drizzle-kit generate --config drizzle.config.ts",
+    "db:migrate": "bunx supabase --workdir ../.. db push --local",
+    "db:push": "drizzle-kit push --config drizzle.config.ts",
+    "db:studio": "drizzle-kit studio --config drizzle.config.ts"
+  },
   "exports": {
     ".": {
       "types": "./src/index.ts",