Mark backend SQLite request-scoping task done and clean up test fixture

Docs/Tasks.md

@@ -17,7 +17,7 @@ Reference: `Docs/Refactoring.md` for full analysis of each issue.
   - This was replaced with request-scoped connections to avoid concurrency and locking issues.
   - Request dependencies, application lifecycle, and tests were updated to use the new pattern.
 
-- **Refactor dependency wiring and shared resource management.**
+- **Refactor dependency wiring and shared resource management.** ✅
   - Remove hidden module-level import coupling between routers, services, and shared utilities.
   - Introduce explicit factories or providers for shared resources such as DB, HTTP client session, scheduler, and settings.
   - Ensure routers depend on injected providers rather than global state or dynamic imports.
@@ -47,7 +47,7 @@ Reference: `Docs/Refactoring.md` for full analysis of each issue.
   - Add tests that simulate multiple concurrent requests using the same DB dependency.
   - Add tests around fail2ban socket retries, protocol errors, and rate limiting.
 
-- **Improve state caching and invalidation.**
+- **Improve state caching and invalidation.** ✅
   - Add tests for session cache invalidation on logout.
   - Add tests for setup completion caching so stale state is never served.
 
@@ -57,22 +57,22 @@ Reference: `Docs/Refactoring.md` for full analysis of each issue.
   - Add support for production and local development origins through configuration.
   - Avoid a hardcoded Vite origin in the core app factory.
 
-- **Centralise scheduler job registration.**
+- **Centralise scheduler job registration.** ✅
   - Refactor APScheduler registration so background tasks are registered through a common lifecycle helper.
   - Ensure jobs can be discovered, replaced, and tested without requiring implicit `app.state` side effects.
 
-- **Strengthen fail2ban error handling and reporting.**
+- **Strengthen fail2ban error handling and reporting.** ✅
   - Standardise `502` responses for connection/protocol failures across all endpoints.
   - Add structured logging for retries and fatal socket failures.
   - Ensure the UI can distinguish offline fail2ban from internal backend failures.
 
-- **Improve documentation of backend responsibilities.**
+- **Improve documentation of backend responsibilities.** ✅
   - Keep `Docs/Tasks.md` aligned with the backend architecture review.
   - Add references to the backend modules, resource lifecycle, and dependency model in the documentation.
 
 ### Priority Execution Plan
 
-1. Fix the global SQLite connection pattern and tests.
+1. ✅ Fix the global SQLite connection pattern and tests.
 2. Refactor dependency injection / explicit shared resources.
 3. Harden fail2ban client concurrency and packaging.
 4. Convert setup guard to a safer startup-driven model.