chore(test): set up integration test framework with postgres

- Generate Drizzle migrations (databases/migrations/)
- Add databases/schema.kit.ts for drizzle-kit (Node-compatible imports)
- Update drizzle.config.ts to use schema.kit.ts
- Add deno tasks: test:unit, test:integration, migrate
- Add tests/helpers/db_integration.ts: testDb, truncateAll, seed helpers
- Add .gitea/workflows/test.yml: CI with postgres service container
- Update lint.yml: run test:unit only (no DB needed)
- Update deploy.yml: add check-code job, gate deploy on it

deno.json

@@ -10,7 +10,10 @@
     "build": "deno run -A --unstable-ffi dev.ts build",
     "preview": "deno run -A --unstable-ffi main.ts",
     "update": "deno run -A -r https://fresh.deno.dev/update .",
-    "test": "deno test -A --no-check tests/"
+    "test": "deno test -A --no-check tests/",
+    "test:unit": "deno test -A --no-check tests/unit/",
+    "test:integration": "deno test -A --no-check tests/integration/",
+    "migrate": "node_modules/.bin/drizzle-kit migrate"
   },
   "lint": {
     "rules": {