Refactor data fetching hooks, add page size lint test

- Simplify useFetchData: remove unused URL building logic
- Add usePolledData initial implementation
- Add router page_size param validation test
- Update API reference docs
- Clean up tasks doc

Docs/Tasks.md

@@ -1,56 +1,3 @@
-### Issue #64: MEDIUM - External Logging Failure Silently Swallowed
-
-**Where found**:
-- `backend/app/main.py:192-213`
-
-**Why this is needed**:
-When Datadog, Papertrail, or Elasticsearch log handler initialization fails, the error is caught, logged as a warning to stdout, and the application continues. In production this means critical logs may never reach the monitoring system, and operators will not know until an incident occurs.
-
-**Goal**:
-External logging failures are surfaced to operators at deployment time.
-
-**What to do**:
-1. Promote the warning to an error and expose it via the health endpoint (Issue #57).
-2. Add a startup check: if `EXTERNAL_LOG_REQUIRED=true` and initialization fails, abort startup.
-3. Emit a metric/alert on initialization failure.
-
-**Possible traps and issues**:
-- Making startup fail on logging issues may be too strict for some environments; make `EXTERNAL_LOG_REQUIRED` optional and default to `false`.
-
-**Docs changes needed**:
-- `Docs/Deployment.md`: document `EXTERNAL_LOG_REQUIRED` and the health check for logging status.
-
-**Doc references**:
-- `backend/app/main.py` logging initialization block
-
----
-
-### Issue #65: MEDIUM - Abort Selector Inconsistency in useFetchData
-
-**Where found**:
-- `frontend/src/hooks/useFetchData.ts:124-131`
-
-**Why this is needed**:
-When a request is aborted, `refresh()` returns the raw response without running the `selector()` function. In non-aborted paths the selector runs. Callers of `refresh()` receive different types depending on the abort state, making the return type unreliable and causing subtle state shape mismatches.
-
-**Goal**:
-`refresh()` returns a consistent type regardless of abort state.
-
-**What to do**:
-1. On abort, return `null` (or a typed sentinel) instead of the raw response, so callers can handle the aborted case explicitly.
-2. Update the TypeScript return type of `refresh()` to reflect the nullable result.
-
-**Possible traps and issues**:
-- Existing callers that ignore the return value are unaffected; callers that use it need to handle `null`.
-
-**Docs changes needed**:
-- `frontend/src/hooks/README.md`: document the `null` return on abort.
-
-**Doc references**:
-- `frontend/src/hooks/README.md`
-
----
-
 ### Issue #67: LOW - Default Page Size Inconsistently Applied Across Routers
 
 **Where found**: