test: add E2E server-detail tests and fill coverage gaps to 83.9%
- Add Playwright E2E for all 5 UX phases (Config/Missions/Mods/Players/Logs)
with ServerDetailPage POM and fully mocked API routes
- Add logger.test.ts: dynamic module re-import pattern for level-gating tests
- Add useUpdateServer + useKillServer tests to useServers.test.tsx
- Add CreateServerPage edge cases: non-admin gate, API error handling, step 2 render
- Add auth.store rehydration and null-branch coverage tests
- Update FRONTEND.md, MODULES.md, API.md, README.md to reflect current state
(167 unit tests, 38 E2E tests, 9 useServers hooks, all UX phases implemented)
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