feat(ops): /operations endpoint + page — live jobs, queue depth, failures

GET /api/v1/operations aggregates active deployments, per-service
deploy-queue depth via Queue.Snapshot(), 24h deployment failures,
cron runs and backups scoped to the caller's projects (admins see all).

Frontend /operations page (Operate nav) shows in-flight count, queued
depth, failures and backup stats with live refetch while deploys are
active. CLI `containr operations` + MCP containr_operations_get.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/backend/internal/cli/root.go

@@ -88,6 +88,7 @@ func init() {
 	rootCmd.AddCommand(commands.AdminCmd)
 	rootCmd.AddCommand(commands.NotificationsCmd)
 	rootCmd.AddCommand(commands.WebhooksCmd)
+	rootCmd.AddCommand(commands.OperationsCmd)
 	rootCmd.AddCommand(commands.UpCmd)
 }