chore: remove ~13,000 lines of dead Electron code

All business logic has been migrated to the REST API server. This removes
obsolete Electron IPC handlers and services that are no longer used:

- Deleted electron/services/ directory (18 files)
- Deleted electron/agent-service.js
- Deleted electron/auto-mode-service.js
- Renamed main-simplified.js → main.js
- Renamed preload-simplified.js → preload.js
- Removed unused dependencies from package.json

The Electron layer now only handles native OS features (10 IPC handlers):
- File dialogs, shell operations, and app info

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/app/electron/preload.js

@@ -1,10 +1,37 @@
-const { contextBridge } = require("electron");
+/**
+ * Simplified Electron preload script
+ *
+ * Only exposes native features (dialogs, shell) and server URL.
+ * All other operations go through HTTP API.
+ */
 
-// Only expose a flag to detect Electron environment
-// All API calls go through HTTP to the backend server
-contextBridge.exposeInMainWorld("isElectron", true);
+const { contextBridge, ipcRenderer } = require("electron");
 
-// Expose platform info for UI purposes
-contextBridge.exposeInMainWorld("electronPlatform", process.platform);
+// Expose minimal API for native features
+contextBridge.exposeInMainWorld("electronAPI", {
+  // Platform info
+  platform: process.platform,
+  isElectron: true,
 
-console.log("[Preload] Electron flag exposed (HTTP-only mode)");
+  // Connection check
+  ping: () => ipcRenderer.invoke("ping"),
+
+  // Get server URL for HTTP client
+  getServerUrl: () => ipcRenderer.invoke("server:getUrl"),
+
+  // Native dialogs - better UX than prompt()
+  openDirectory: () => ipcRenderer.invoke("dialog:openDirectory"),
+  openFile: (options) => ipcRenderer.invoke("dialog:openFile", options),
+  saveFile: (options) => ipcRenderer.invoke("dialog:saveFile", options),
+
+  // Shell operations
+  openExternalLink: (url) => ipcRenderer.invoke("shell:openExternal", url),
+  openPath: (filePath) => ipcRenderer.invoke("shell:openPath", filePath),
+
+  // App info
+  getPath: (name) => ipcRenderer.invoke("app:getPath", name),
+  getVersion: () => ipcRenderer.invoke("app:getVersion"),
+  isPackaged: () => ipcRenderer.invoke("app:isPackaged"),
+});
+
+console.log("[Preload] Electron API exposed (simplified mode)");