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.

web/src/routes/+layout.svelte

@@ -23,7 +23,7 @@
 
 	const { children }: Props = $props();
 
-	type NavCountKey = 'projects' | 'sites' | 'stacks' | 'proxies' | 'eventsErrors';
+	type NavCountKey = 'projects' | 'sites' | 'stacks' | 'proxies' | 'containers' | 'eventsErrors';
 
 	const navItems: ReadonlyArray<{
 		href: string;
@@ -37,7 +37,7 @@
 		{ href: '/projects', labelKey: 'nav.projects', icon: 'projects', countKey: 'projects' },
 		{ href: '/sites', labelKey: 'nav.sites', icon: 'globe', countKey: 'sites' },
 		{ href: '/stacks', labelKey: 'nav.stacks', icon: 'stacks', countKey: 'stacks' },
-		{ href: '/containers', labelKey: 'nav.containers', icon: 'containers' },
+		{ href: '/containers', labelKey: 'nav.containers', icon: 'containers', countKey: 'containers' },
 		{ href: '/deploy', labelKey: 'nav.deploy', icon: 'deploy' },
 		{ href: '/proxies', labelKey: 'nav.proxies', icon: 'proxies', countKey: 'proxies' },
 		{ href: '/events', labelKey: 'nav.events', icon: 'events', countKey: 'eventsErrors', alert: true },