feat(static): inline static-source plugin; drop phantom-row adapter

Lift the static-site deploy pipeline from internal/staticsite/manager.go
into internal/workload/plugin/source/static/ so plugin-native static
workloads operate directly on plugin.Workload + the containers table +
workload_env. The cmd/server/static_backend.go phantom-row adapter is
gone; the legacy static_sites table is no longer touched on plugin
deploys.

Backend
- new state.go: runtimeState (last_commit_sha, last_sync_at,
  last_error, status) persisted in containers.extra_json under the
  deterministic row id <workloadID>:site
- per-workload sync.Mutex serializes saveState read-modify-write so
  parallel deploys for the same workload can't race container_id /
  proxy_route_id writes
- extra_json round-trips through map[string]json.RawMessage so
  unknown keys survive — typed runtimeStateKeys are stripped before
  merge so clearing a typed field actually drops the key
- new env.go reads workload_env (replaces static_site_secrets for
  plugin-native sites); decrypt-failure logs and skips one entry
  rather than failing the whole deploy
- new build.go ports prepareDenoBuild + prepareStaticBuild + copyDir;
  copyDir uses filepath.WalkDir + Lstat to refuse symlinks and
  non-regular files
- new deploy.go is the ~300-line core; intent.Reason gates force vs
  skip-if-no-changes; success-path saveState failure rolls back
  container + proxy route and writes "failed" state (no orphans)
- new teardown.go combines Remove + Stop; idempotent on
  never-deployed workloads
- new reconcile.go refreshes container state from Docker; flips
  runtimeState.Status to failed when the container is missing/crashed

Hardening (from go-reviewer + security-reviewer subagent passes;
1 CRITICAL + 5 HIGH + 3 MEDIUM addressed before merge)
- path-traversal defense in all 3 providers (gitea_content,
  github_provider, gitlab_provider): reject tree entries whose
  resolved local path escapes destDir
- verifyDownloadInsideRoot walks the build dir post-download as a
  second line of defense
- sanitizeError redacts the access token, collapses to one line, and
  clamps to 240 bytes before persisting to extra_json or fanning out
  to the notification webhook
- container/image/volume names suffixed with workload-id short prefix
  (workload name is not UNIQUE in schema)
- primaryDomain reads settings.Domain to complete a bare subdomain
  face into a full FQDN (matches legacy Manager behavior)
- ctx-aware health-check sleep
- json.Marshal for event metadata (was fmt.Sprintf JSON template)
- strings.HasPrefix for failed-status detection (was brittle slice
  expression)

Wire-up
- cmd/server/main.go: removed wireStaticBackend(...) call; existing
  blank import on _ ".../source/static" drives init() registration
- cmd/server/static_backend.go deleted

Doc
- WORKLOAD_REFACTOR_TODO: static port marked DONE; next focus is
  the hard legacy cutover (drop /api/projects, /api/stacks,
  /api/sites, /api/stages + their tables, internal/stack +
  internal/staticsite packages, frontend /projects /stacks /sites)

Behavior notes for operators
- plugin-native static workloads no longer write to static_sites;
  legacy /api/sites/* still serves original rows unchanged
- legacy tinyforge.static-site / .static-site-name container labels
  dropped on plugin deploys; canonical tinyforge.workload.id / .kind
  cover ownership
- container/image/volume names gained an 8-char ID suffix
  (e.g. dw-site-mysite-a1b2c3d4); legacy-deployed sites keep the
  old shape until redeployed through the plugin path

cmd/server/main.go

@@ -348,11 +348,11 @@ func main() {
 	// Initialize static site manager and health checker.
 	staticSiteMgr := staticsite.NewManager(db, dockerClient, proxyProvider, eventBus, notifier, encKey)
 	webhookHandler.SetSiteSyncTriggerer(staticSiteMgr)
-	// Wire the plugin static source's backend to the manager. After this
-	// call the "static" kind appears in /api/hooks/kinds and the /apps/new
-	// picker; before it, the source registers no kind, so the frontend
-	// silently omits it.
-	wireStaticBackend(db, staticSiteMgr)
+	// The plugin static source registers itself eagerly in its init()
+	// now that the deploy pipeline is implemented inline (see
+	// internal/workload/plugin/source/static). The legacy Manager kept
+	// here keeps the /api/sites/* HTTP routes alive during the cutover
+	// window.
 	staticSiteHealth := staticsite.NewHealthChecker(db, dockerClient, staticSiteMgr)
 	if err := staticSiteHealth.Start("2m"); err != nil {
 		slog.Warn("failed to start static site health checker", "error", err)