docs(sdk): éclate et étend la documentation SDK par sujet

Remplace le README monolithique par un point d'entrée vers des pages dédiées
(manifest, activation/contexte, menus, commandes/feedback, layouts React,
fenêtres, services, packaging/distribution) pour couvrir #142-#144 et
faciliter la navigation.

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

docs/services.md

@@ -0,0 +1,68 @@
+# Services
+
+`ctx.services` is the stable public host facade. It is available to plugins that
+declare `ui` or `tooling` capabilities.
+
+```json
+{
+  "capabilities": ["ui", "tooling"]
+}
+```
+
+## Workspace
+
+`services.workspace` reads the focused/current project, project context and
+project-owned files. Paths are relative to the project root; hosts reject
+absolute paths and traversal outside the workspace.
+
+Key APIs:
+
+- `getCurrentProject()`
+- `getProjectRoot(projectId?)`
+- `readProjectContext(projectId?)`
+- `updateProjectContext(content, projectId?)`
+- `readTextFile(path, projectId?)`
+- `writeTextFile(path, content, projectId?)`
+- `readBinaryFile(path, projectId?)`
+- `writeBinaryFile(path, bytes, projectId?)`
+- `listDirectory(path?, projectId?)`
+- `stat(path, projectId?)`
+- `watch(path, handler, projectId?)`
+- `queryStructure(query?)`
+
+## Tasks
+
+`services.tasks` launches and inspects host-managed command tasks.
+
+Use `runCommand()` only after preconditions are satisfied. `ownerAgentId` must be
+a real agent id when work belongs to an agent workflow.
+
+## Tooling
+
+`services.tooling.diagnose()` checks executables, environment values and files
+from the host-controlled runtime.
+
+## Events
+
+`services.events.subscribe()` provides best-effort bounded subscriptions to
+public plugin events such as workspace file changes and background task changes.
+Dispose subscriptions when no longer needed.
+
+## Config
+
+`services.config` reads and updates structured JSON documents in project-owned
+locations. Use it for configuration the user expects to review/version.
+
+## Terminal
+
+`services.terminal` opens, reattaches and closes terminal sessions:
+
+- `open({ cwd?, rows?, cols?, onData? })`
+- `reattach(sessionId, { onData? })`
+- `close(sessionId)`
+
+## Windows
+
+`services.windows.open({ layoutType, state? })` opens a detached OS window for
+one of the calling plugin's declared layout contributions. See
+[Windows](windows.md).