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/features/plugins/PluginRuntimeProvider.tsx

@@ -73,6 +73,8 @@ export function PluginRuntimeProvider({ children, value: injected }: PluginRunti
           terminal: gateways.terminal,
           agents: gateways.agent,
           system: gateways.system,
+          workState: gateways.workState,
+          focusedProject: gateways.focusedProject,
         }),
       )
       .then((result) => {