fix: Provider sync on every startup + sandbox fixes (v2.0.4)

Critical fixes:
- ALWAYS sync active AG X provider to endpoints.json on startup
  (previously only synced on first run, causing LS to use stale data)
- Add --no-sandbox to proxy process spawns (fixes SIGTRAP crash on Linux)
- Add --no-sandbox for all Electron modes (not just headless)
- Add --ag-reset flag to re-trigger welcome screen
- Bump version to 2.0.4

Root causes fixed:
1. endpoints.json was never updated after first-run, so LS used wrong provider
2. Electron child processes (translation proxy) crashed due to SUID sandbox
3. No way to re-show provider selection after initial setup

dist/languageServer.js

@@ -238,7 +238,7 @@ function ensureProxyStarted() {
             // Use Electron's built-in Node.js to run our translation proxy
             const proxyScript = path_1.default.join(__dirname, 'services', 'translationProxy.js');
             const nodeBin = process.execPath;
-            _proxyProcess = (0, child_process_1.spawn)(nodeBin, [proxyScript], {
+            _proxyProcess = (0, child_process_1.spawn)(nodeBin, ['--no-sandbox', proxyScript], {
                 stdio: 'ignore',
                 detached: true,
                 env: { ...process.env }