backend: GDPR export + retention cleanups + worker metrics (BE-1/2/3)

BE-3 observability: expose the worker's Prometheus metrics on :6060/metrics
(apns/fcm/asynq histograms + a new cache_ops_total counter were recorded all
along but never scraped — which is why those dashboard panels read empty); add
the worker containerPort, the vmagent worker scrape job, and two additive
NetworkPolicies. Instrument cache Get/Set hit/miss.

BE-2 retention: three periodic Asynq cleanup crons mirroring the reminder-log
cleanup — notifications (90d), webhook dedup log (180d), audit_log (365d).

BE-1 GDPR data export: POST /api/auth/export/ enqueues a low-priority Asynq job
that gathers all of the user's data (owned residences + their tasks/contractors/
documents/share-codes, plus profile/notifications/prefs/push-tokens/subscription/
audit log), zips one JSON file per category, and emails it as an attachment.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/worker/scheduler.go

@@ -21,8 +21,17 @@ const (
 	// Moves the ~1-1.5s of synchronous APNs+SMTP+B2-fetch work out of the
 	// POST /api/task-completions/ request path.
 	TypeTaskCompletedNotification = "notification:task_completed"
+
+	// TypeDataExport is emitted by POST /api/auth/export/. The worker gathers
+	// all of the user's data into a zip and emails it (GDPR data portability).
+	TypeDataExport = "user:data_export"
 )
 
+// DataExportPayload carries just the user id; the worker re-fetches all rows.
+type DataExportPayload struct {
+	UserID uint `json:"user_id"`
+}
+
 // TaskCompletedNotificationPayload carries only the IDs needed for the
 // worker to re-fetch the canonical Task + TaskCompletion rows. Keeping the
 // payload to IDs (vs. full model graphs) keeps the Redis queue cheap and
@@ -93,6 +102,26 @@ func (c *TaskClient) EnqueueWelcomeEmail(to, firstName, code string) error {
 	return nil
 }
 
+// EnqueueDataExport enqueues a GDPR data-export task for a user. The worker
+// gathers the user's data, zips it, and emails it. Low priority — there's no
+// rush, and it shouldn't compete with notifications for the critical queue.
+func (c *TaskClient) EnqueueDataExport(userID uint) error {
+	payload, err := BuildDataExportPayload(userID)
+	if err != nil {
+		return err
+	}
+
+	task := asynq.NewTask(TypeDataExport, payload)
+	_, err = c.client.Enqueue(task, asynq.Queue("low"), asynq.MaxRetry(3))
+	if err != nil {
+		log.Error().Err(err).Uint("user_id", userID).Msg("Failed to enqueue data export")
+		return err
+	}
+
+	log.Info().Uint("user_id", userID).Msg("Data export task enqueued")
+	return nil
+}
+
 // EnqueueVerificationEmail enqueues a verification email task
 func (c *TaskClient) EnqueueVerificationEmail(to, firstName, code string) error {
 	payload, err := BuildVerificationEmailPayload(to, firstName, code)