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

drizzle.config.ts

@@ -3,7 +3,7 @@ import process from "node:process";
 
 export default defineConfig({
   dialect: "postgresql",
-  schema: "./databases/schema.ts",
+  schema: "./databases/schema.kit.ts",
   out: "./databases/migrations",
   dbCredentials: {
     host: process.env.POSTGRES_HOST!,