Replace CI lint jobs with backend, frontend, and e2e test jobs

Lint, formatting, and type checks are already enforced by prek pre-commit
hooks, so CI now focuses on running the actual test suites instead.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.beans/nuzlocke-tracker-yzpb--implement-unit-integration-tests.md

@@ -1,11 +1,11 @@
 ---
 # nuzlocke-tracker-yzpb
 title: Implement Unit & Integration Tests
-status: todo
+status: completed
 type: epic
 priority: high
 created_at: 2026-02-10T09:32:47Z
-updated_at: 2026-02-21T11:29:02Z
+updated_at: 2026-02-21T13:00:44Z
 ---
 
 Add comprehensive unit and integration test coverage to both the backend (FastAPI/Python) and frontend (React/TypeScript). The project currently has zero tests — pytest is configured in pyproject.toml with pytest-asyncio and httpx, but no actual test files exist. The frontend has no test tooling at all.
@@ -21,7 +21,7 @@ Add comprehensive unit and integration test coverage to both the backend (FastAP
 ## Success Criteria
 
 - [x] Backend test infrastructure is set up (conftest, fixtures, test DB)
-- [ ] Backend schemas and services have unit test coverage
+- [x] Backend schemas and services have unit test coverage
 - [x] Backend API endpoints have integration test coverage
 - [x] Frontend test infrastructure is set up (Vitest, RTL)
 - [x] Frontend utilities and hooks have unit test coverage