add-integration

# Adding a new third-party integration ## Planner Entry Load `/spec-driven-development` for a substantial integration. The primary session plans, investigates existing patterns, and may directly implement a small localized slice. Delegate only independent backend, frontend, test, or documentation packets whose isolation clearly helps; workers do not spawn. Jira and Linear are the model: per-workspace credentials, a 90s auth-health poller, a settings page with status banner + reconnect CTA, link/import buttons that gate on availability. New integrations should **reuse the shared shapes** rather than copying either. ## Backend (`apps/backend/internal/<name>/`) - Mirror the package layout: `service.go`, `store.go`, `client.go`, `provider.go`, `handlers.go`, `models.go`, `poller.go`. Expose `Provide(writer, reader *sqlx.DB, secrets SecretStore, eventBus bus.EventBus, log *logger.Logger) (*Service, func() error, error)`. Pass `nil` for `eventBus` when the integration doesn't publish events; both Jira and Linear take and use it for issue-watch publishing. - Use `internal/integrations/secretadapter` instead of writing your own upsert wrapper around `secrets.SecretStore`. The adapter satisfies any per-integration `SecretStore` interface shaped as `{Reveal, Set, Delete, Exists}`. - Use `internal/integrations/healthpoll` for the auth-health loop. Implement the `Prober` interface (`ListConfiguredWorkspaces` + `RecordAuthHealth`) on a small adapter and let `healthpoll.New("name", pr...