feat(electron): add desktop application support with electron (#344)

* feat(electron): add desktop application support with electron

- implement complete Electron main process architecture with window management,
  app menu, IPC handlers, and settings window
- integrate Next.js server for production builds with embedded standalone server
- add configuration management with persistent storage and env file support
- create preload scripts with secure context bridge for renderer communication
- set up electron-builder configuration for multi-platform packaging (macOS,
  Windows, Linux)
- add GitHub Actions workflow for automated release builds
- include development scripts for hot-reload during Electron development

* feat(electron): enhance security and stability

- encrypt API keys using Electron safeStorage API before persisting to disk
- add error handling and rollback for preset switching failures
- extract inline styles to external CSS file and remove unsafe-inline from CSP
- implement dynamic port allocation with automatic fallback for production builds

* fix(electron): add maintainer field for Linux .deb package

- add maintainer email to linux configuration in electron-builder.yml
- required for building .deb packages

* fix(electron): use shx for cross-platform file copying

- replace Unix-only cp -r with npx shx cp -r
- add shx as devDependency for Windows compatibility

* fix(electron): fix runtime icon path for all platforms

- use icon.png directly instead of platform-specific formats
- electron-builder handles icon conversion during packaging
- macOS uses embedded icon from app bundle, no explicit path needed
- add icon.png to extraResources for Windows/Linux runtime access

* fix(electron): add security warning for plaintext API key storage

- warn user when safeStorage is unavailable (Linux without keyring)
- fail secure: throw error if encryption fails instead of storing plaintext
- prevent duplicate warnings with hasWarnedAboutPlaintext flag

* fix(electron): add remaining review fixes

- Add Windows ARM64 architecture support
- Add IPC input validation with config key whitelist
- Add server.js existence check before starting Next.js server
- Make afterPack throw error on missing directories
- Add workflow permissions for release job

---------

Co-authored-by: dayuan.jiang <jdy.toh@gmail.com>

electron/preload/settings.ts

@@ -0,0 +1,35 @@
+/**
+ * Preload script for settings window
+ * Exposes APIs for managing configuration presets
+ */
+import { contextBridge, ipcRenderer } from "electron"
+
+// Expose settings API to the renderer process
+contextBridge.exposeInMainWorld("settingsAPI", {
+    // Get all presets
+    getPresets: () => ipcRenderer.invoke("config-presets:get-all"),
+
+    // Get current preset ID
+    getCurrentPresetId: () =>
+        ipcRenderer.invoke("config-presets:get-current-id"),
+
+    // Get current preset
+    getCurrentPreset: () => ipcRenderer.invoke("config-presets:get-current"),
+
+    // Save (create or update) a preset
+    savePreset: (preset: {
+        id?: string
+        name: string
+        config: Record<string, string | undefined>
+    }) => ipcRenderer.invoke("config-presets:save", preset),
+
+    // Delete a preset
+    deletePreset: (id: string) =>
+        ipcRenderer.invoke("config-presets:delete", id),
+
+    // Apply a preset (sets environment variables and restarts server)
+    applyPreset: (id: string) => ipcRenderer.invoke("config-presets:apply", id),
+
+    // Close settings window
+    close: () => ipcRenderer.send("settings:close"),
+})