refactor(workload): finalize containers index + post-review hardening

Wraps up the workload refactor with the fixes that came out of the multi-agent
code review (see docs/plans/workload-refactor.md "What actually shipped").

Backend:
- store.ReconcileContainer: separate write path so the 30s reconciler tick no
  longer overwrites deployer-owned fields (subdomain, proxy_route_id,
  npm_proxy_id, image_tag).
- Container.stage_id column + index; ListProxyRoutes / ListContainersByStageID
  join via stage_id (survives stage rename), with legacy fallback to
  (project_id, role=stage_name).
- Reconciler: workload-existence check (rejects forged tinyforge.workload.id
  labels), skips inventing project-kind rows, child-context cancel before
  wg.Wait() on shutdown.
- Transactional CRUD across projects / stacks / static_sites: parent UPDATE
  and workload sync land in one transaction so secret rotations are durable.
- Webhook routing reads exclusively through workloads.webhook_secret; legacy
  GetProjectByWebhookSecret / GetStaticSiteByWebhookSecret fallback removed.
- store.GetStackByComposeProjectName + indexed lookup (no more full-table
  stack scan per compose container per tick).
- store.ListMissingSweepRows: filtered query for the missing-sweep.
- /api/instances/* handlers verify (workload_id, role) match URL
  (project_id, stage_name) before mutating — closes the cross-project
  hijack the security review flagged.
- extra_json no longer referenced from Go (column kept on disk for now).

Frontend:
- WorkloadContainers.svelte: generic detail-page panel reusable by stack and
  site detail pages.
- Containers page polish: client-side kind/state filters over an unfiltered
  fetch, URL-synced filters, race-safe loads via sequence number, EN+RU i18n,
  sidebar counter via navCounts.containers.

Misc:
- scripts/dev-server.sh: tolerate empty netstat grep result.
- .gitignore: ignore docker-watcher binaries, .claude/worktrees/, .facts-sync.json.

internal/store/workloads.go

@@ -30,9 +30,6 @@ func (s *Store) CreateWorkload(w Workload) (Workload, error) {
 	if w.ID == "" {
 		w.ID = uuid.New().String()
 	}
-	if w.AppID == "" {
-		w.AppID = ""
-	}
 	w.CreatedAt = Now()
 	w.UpdatedAt = w.CreatedAt
 
@@ -148,7 +145,10 @@ func (s *Store) UpdateWorkload(w Workload) error {
 	if err != nil {
 		return fmt.Errorf("update workload: %w", err)
 	}
-	n, _ := result.RowsAffected()
+	n, err := result.RowsAffected()
+	if err != nil {
+		return fmt.Errorf("rows affected: %w", err)
+	}
 	if n == 0 {
 		return fmt.Errorf("workload %s: %w", w.ID, ErrNotFound)
 	}
@@ -163,7 +163,10 @@ func (s *Store) DeleteWorkload(id string) error {
 	if err != nil {
 		return fmt.Errorf("delete workload: %w", err)
 	}
-	n, _ := result.RowsAffected()
+	n, err := result.RowsAffected()
+	if err != nil {
+		return fmt.Errorf("rows affected: %w", err)
+	}
 	if n == 0 {
 		return fmt.Errorf("workload %s: %w", id, ErrNotFound)
 	}