feat(sdk): contrat permissions.workspaceExec pour l'exécution contrôlée via l'hôte — #346

Cadrage capacités plugin SCM (#346): le manifeste plugin gagne
permissions.workspaceExec.allow — règles d'exécution contrôlée par l'hôte
(commande bare ASCII résolue sans shell, argv exact avec jeton `*` en
suffixe, cwd project-relative sûr, effect read/write/network/destructive,
64 règles max) — au lieu de lectures ad hoc du store interne .git.
Validation manifeste + exports runtime/index + docs README/manifest/
services + auto-check script étendu (règles valides acceptées, règles
unsafe rejetées).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -14,7 +14,8 @@ exports `activate(ctx)`.
 - [Commands And Feedback](docs/commands-and-feedback.md): command return values, skipped work and background tasks.
 - [Layouts With React](docs/layouts-react.md): React/JSX/hooks layout authoring with host-provided React.
 - [Windows](docs/windows.md): opening plugin layouts in detached OS windows.
-- [Services](docs/services.md): workspace, tasks, tooling, events, config, terminal and windows facades.
+- [Services](docs/services.md): workspace files and bounded `workspace.execTool`, tasks,
+  tooling, events, config, terminal and windows facades.
 - [Packaging And Distribution](docs/packaging-distribution.md): build output, archive layout, hot reload and dependency rules.
 - [Codex Skills And IdeA Plugins](docs/codex-skills-and-idea-plugins.md): separate IdeA-native plugin skills from Codex plugin discovery.
 - [Project Plugin Assignments](docs/project-plugin-assignments.md): enable plugins per project and assign skills and MCP tools to agents.
@@ -23,6 +24,12 @@ The installable example lives in [`examples/hello-plugin`](examples/hello-plugin
 It demonstrates a menu command, storage, background-task feedback, a React layout
 component and `services.windows.open(...)`.
 
+For short project-scoped external tools, use
+`ctx.services.workspace.execTool()` with an explicit manifest
+`permissions.workspaceExec` allow rule. See [Services](docs/services.md) and
+[Manifest](docs/manifest.md). The primitive is generic and does not expose a
+native Git/SCM API.
+
 ## Install
 
 ```sh