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/packaging-distribution.md

@@ -0,0 +1,76 @@
+# Packaging And Distribution
+
+A plugin archive is a ZIP file whose root contains `idea-plugin.json`.
+
+```text
+hello-plugin-0.1.0.zip
+├── idea-plugin.json
+├── README.md
+└── dist/
+    ├── index.js
+    ├── constants.js
+    └── core/
+        ├── layout.js
+        ├── storage.js
+        └── workspace.js
+```
+
+The manifest `main` field must point to an emitted file inside the archive:
+
+```json
+{
+  "main": "dist/index.js"
+}
+```
+
+## Module Resolution
+
+IdeA loads `main` as ESM and serves package-relative imports from the plugin
+package. This is supported:
+
+```js
+import { Dashboard } from "./core/layout.js";
+```
+
+For React, import bare host modules normally:
+
+```js
+import { useState } from "react";
+import { jsx } from "react/jsx-runtime";
+```
+
+IdeA resolves React/ReactDOM bare imports to the host instance. Other bare
+dependencies are not host-resolved. Bundle or vendor third-party dependencies
+other than React/ReactDOM into package-relative files.
+
+## TypeScript Build
+
+The hello plugin uses plain `tsc`:
+
+```sh
+npm run build
+npm run build:hello-plugin
+```
+
+For React layouts, configure JSX:
+
+```json
+{
+  "compilerOptions": {
+    "jsx": "react-jsx",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext"
+  }
+}
+```
+
+## Archive Build
+
+The SDK example can be packaged with:
+
+```sh
+npm run package:hello-plugin
+```
+
+The resulting archive has no wrapping parent directory and is ready for IdeA's
+plugin installer.