v2.0.5: Fix E2E flow - proxy, welcome screen, provider sync

Critical fixes:
- Translation proxy now uses system Node.js (not Electron binary)
- Removed duplicate proxy start causing port conflicts
- Added port availability check before spawning proxy
- Fixed welcome:choice double resolve()
- Fixed settings.html close using deprecated remote
- Fixed translationProxy /v1 for openai-compat backends
- Proxy no longer detached/unref - properly tracked as child
- SingletonLock cleanup on startup

Verified E2E:
- Welcome screen on first run ✓
- Provider selection works ✓
- Settings save + sync ✓
- Translation proxy starts correctly ✓
- LS connects to proxy ✓
- --ag-reset works ✓

dist/services/translationProxy.js

@@ -78,6 +78,10 @@ function applyConfig(cfg) {
   PORT = cfg.port || 48080;
   BACKEND = cfg.backend_type || "openai-compat";
   TARGET_URL = cfg.target_url || "http://localhost:11434/v1";
+  // Ensure /v1 suffix for openai-compat backends
+  if (BACKEND === "openai-compat" && !TARGET_URL.endsWith("/v1")) {
+    TARGET_URL = TARGET_URL.replace(/\/+$/, "") + "/v1";
+  }
   API_KEY = cfg.api_key || "";
   OAUTH_PROVIDER = cfg.oauth_provider || "";
   REASONING_ENABLED = cfg.reasoning_enabled !== undefined ? cfg.reasoning_enabled : true;