chore(release): passe la version à 0.2.0

Bump des manifestes (crates Rust + frontend) et des lockfiles vers
0.2.0 en préparation de la release. Ajoute /node_modules à .gitignore
(tooling installé à la racine, jamais versionné).

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

frontend/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "idea-frontend",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "idea-frontend",
-      "version": "0.1.0",
+      "version": "0.2.0",
       "dependencies": {
         "@tauri-apps/api": "^2.1.1",
         "@tauri-apps/plugin-dialog": "^2.7.1",