feat(sdk,plugins): ajoute capability tooling et services runtime publics (workspace/terminal/tasks)

- capability manifeste tooling supportée backend + transport runtime catalog
- ctx.services publique côté SDK/runtime, gated par tooling
- surface honnête: workspace, terminal, et tasks en observation/contrôle uniquement
- docs/exemple/tests mis à jour
- QA PASS sur feature/sdk-plugin-tooling-build-debug-surface

frontend/src/plugins/runtime/index.ts

@@ -18,4 +18,19 @@ export {
   type PluginLoadFailure,
   type PluginLoadResult,
 } from "./loader";
+export {
+  createPluginServices,
+  type BackgroundTaskOutputAttachment,
+  type BackgroundTaskRetryResult,
+  type BackgroundTaskService,
+  type BackgroundTaskStatus,
+  type PluginServices,
+  type TerminalOpenOptions,
+  type TerminalReattachOptions,
+  type TerminalReattachResult,
+  type TerminalService,
+  type TerminalSession,
+  type WorkspaceProject,
+  type WorkspaceService,
+} from "./services";
 export { evaluateWhen, type WhenContext, type WhenEvalResult, type WhenVariable } from "./when";