* fix(github): stop PR polling for archived tasks
The PR watcher kept making GitHub API calls for tasks the user had
archived, wasting rate limit and surfacing stale checks. Hide archived
and orphaned watches from the poller via an INNER JOIN on tasks, and
proactively prune watches when task.updated (archived_at set) or
task.deleted events fire. Closes#989.
* fix(github): address review comments on PR watch pruning
- Detect archived_at from a non-empty string value instead of key
presence, so a future null/zero archived_at in the task event payload
doesn't silently prune watches on non-archive updates.
- Track task-event subscriptions on the Service and release them in the
provider cleanup so handlers don't accumulate if the service is torn
down and re-created while the event bus persists.
- Propagate RowsAffected errors from DeletePRWatchesByTaskID instead of
silently discarding them.
Carlos Florêncio