refactor(workload): plugin architecture wave + apps UI + volume scopes

Completes the workload-first refactor's plugin layer:

- internal/workload/plugin/ — Source/Trigger plugin contract,
  registry, types (Workload, DeploymentIntent, InboundEvent,
  PublicFace). Self-registering init() pattern + blank-import
  in cmd/server/main.go.
- Source plugins: image (blue-green with multi-face proxy routing),
  compose, static. Trigger plugins: registry, git, manual.
- internal/deployer/dispatch.go — DispatchPlugin/Teardown/Reconcile
  seam routing the legacy deployer through plugins.
- internal/api/workload_*.go — REST surface: workloads, env,
  volumes, chain (parent/children), promote-from. hooks.go
  serves /api/hooks/kinds/{kind}/schema for the wizard.
- internal/store: workload_env (encrypt-at-rest secrets) and
  workload_volumes tables, keyed on workload_id.
- cmd/server/static_backend.go — phantom-row adapter delegating
  the static source plugin to the legacy staticsite.Manager
  (deleted at hard cutover once the static inline port lands).
- web/src/routes/apps/ — /apps list + /apps/new wizard +
  /apps/[id] detail with kind-aware compose / image / static
  forms (Advanced JSON toggle), env panel, volumes panel,
  webhook panel, chain panel, manual deploy.

Volume scope generalization (v2 resolver):

- internal/volume.ResolveWorkloadPath (workload-keyed, sits
  next to legacy ResolvePath). Honors all VolumeScope values:
  absolute, ephemeral, instance, stage, project, project_named,
  named. internal/workload/plugin/source/image/image.go
  computeMounts wires settings + imageTag through. Coverage in
  internal/volume/resolver_test.go (portable Linux/Windows via
  t.TempDir).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/api/instances.go

@@ -10,6 +10,7 @@ import (
 	"github.com/go-chi/chi/v5"
 
 	"github.com/alexei/tinyforge/internal/store"
+	"github.com/alexei/tinyforge/internal/workload/plugin"
 )
 
 // listInstances handles GET /api/projects/{id}/stages/{stage}/instances.
@@ -216,10 +217,21 @@ func (s *Server) controlInstance(w http.ResponseWriter, r *http.Request, action
 	})
 }
 
-// DeployTriggerer is the interface for triggering deployments.
+// DeployTriggerer is the interface for triggering deployments. The legacy
+// project/stage methods continue to drive image-tag CI promotions; the
+// plugin methods (DispatchPlugin / DispatchTeardown / DispatchReconcile)
+// route through the unified Source registry. Both surfaces are kept on
+// one interface so the API layer holds a single deployer reference and
+// the type assertion in hooks.go / workloads_plugin.go is replaced with
+// compile-time checking.
 type DeployTriggerer interface {
 	TriggerDeploy(ctx context.Context, projectID, stageID, imageTag string) error
 	AsyncTriggerDeploy(ctx context.Context, projectID, stageID, imageTag string) (string, error)
+
+	DispatchPlugin(ctx context.Context, w plugin.Workload, intent plugin.DeploymentIntent) error
+	DispatchTeardown(ctx context.Context, w plugin.Workload) error
+	DispatchReconcile(ctx context.Context, w plugin.Workload) error
+	PluginDeps() plugin.Deps
 }
 
 // resolveAndAuthorizeInstance loads the container row identified by {iid} and