feat: add web testing foundation with infra-backed suites (#349)

* feat: add web test framework with infra-backed suites

* fix: honor DATABASE_URL env in integration prepare script

* fix: apply web test review feedback

* fix: streamline web test infra lifecycle and workflow scope

apps/web/TESTING.md

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+# Testing in `apps/web`
+
+This app now supports four testing layers:
+
+- Unit tests (`*.unit.test.ts`)
+- tRPC tests (`*.trpc.test.ts`)
+- API tests (`*.api.test.ts`)
+- Infra-backed integration tests (`*.integration.test.ts`)
+
+## Stack
+
+- Runner: Vitest
+- Coverage: V8 provider via `@vitest/coverage-v8`
+- Path aliases: `vite-tsconfig-paths`
+- Infra for integration: PostgreSQL + Redis via Docker Compose
+
+## Commands
+
+From repo root:
+
+- `pnpm test:web`
+- `pnpm test:web:all`
+- `pnpm test:web:unit`
+- `pnpm test:web:trpc`
+- `pnpm test:web:api`
+- `pnpm test:web:integration`
+- `pnpm test:web:integration:full`
+
+Infra helpers:
+
+- `pnpm test:infra:up`
+- `pnpm test:infra:down`
+
+Full integration flow:
+
+1. `pnpm test:infra:up`
+2. `pnpm test:web:integration:full` (or `pnpm test:web:all`)
+3. `pnpm test:infra:down`
+
+## Infra configuration
+
+- Compose file: `docker/testing/compose.yml`
+- Postgres: `127.0.0.1:54329` (`usesend_test`)
+- Redis: `127.0.0.1:6380` (test DB index `15`)
+
+The default test env is bootstrapped in `src/test/setup/setup-env.ts`.
+Override values by exporting env vars before running tests.
+
+## Test layout
+
+- `src/test/setup/*`: global test bootstrap
+- `src/test/integration/*`: integration reset helpers
+- Tests colocated next to modules under `src/**`
+
+## Notes
+
+- Integration suites only run when `RUN_INTEGRATION=true`.
+- Integration helpers truncate all public Postgres tables (except `_prisma_migrations`) and flush Redis DB before each test.
+- Queue and Redis tests rely on `REDIS_URL` test DB index to avoid polluting local dev state.
+
+## CI
+
+GitHub Actions workflow: `.github/workflows/test-web.yml`
+
+The workflow runs unit, tRPC, API, and integration tests with PostgreSQL and Redis services.