Release 0.3.0: compiler service wired into the IDE

- Native modula2-compiler extension (RPC contract, async gm2
  backend, Build/Build File/Clean/Rebuild/Run/Detect commands)
- Bundled into browser and electron apps; browser bundle boots
- Root prepare script fixed; workbench placeholder retired

package.json

@@ -1,7 +1,7 @@
 {
   "private": true,
   "name": "modula2-ide",
-  "version": "0.2.0",
+  "version": "0.3.0",
   "description": "GNU Modula-2 IDE built on Eclipse Theia",
   "engines": {
     "node": ">=24",