fix(hooks): handle enabled toggling explicitly in useSmartPolling (#570)

[Proxima84-code]

Summary

Fixes #570.

In useSmartPolling, toggling enabled from true to false cleared the interval timer but deliberately refrained from dispatching STOP_POLLING to avoid unmount state warnings. Consequently, isPolling remained true, misleading consumers like useBountyStatus into reporting active polling. Furthermore, toggling back from false to true was skipped because hasInitialized.current remained true, permanently pausing polling until a tab visibility change.

Changes

• Unmount separation: Dedicated an unmount-only cleanup effect (useEffect(() => () => { isMountedRef.current = false; }, [])) following the useClaimRace lacks the isMountedRef unmount guard that its sibling hook useSmartPolling already has #361 pattern, ensuring unmount safeguards do not interfere with hook parameter transitions.
• Explicit enabled handling:
  • Toggling enabled: false clears the active interval and dispatches STOP_POLLING.
  • Toggling enabled: true starts polling immediately, schedules the interval, and dispatches START_POLLING when active.
• Callback stability: Stored caller callbacks (fetchFn, compareFn, onDataChange) in refs so polling cycles remain stable across component re-renders.
• Unit tests (src/hooks/useSmartPolling.test.ts): Added comprehensive test coverage verifying:
  1. Polling on mount when enabled=true.
  2. Idle state when mounted with enabled=false.
  3. enabled: true -> false stopping the interval and setting isPolling: false.
  4. enabled: false -> true immediately restarting polling and rescheduling the timer.
  5. In-flight unmount safety without state warnings.

[vercel]

@Proxima84-code is attempting to deploy a commit to the chonilius' projects Team on Vercel.

A member of the Team first needs to authorize it.