Implement complete native menu system with keyboard accelerators

This commit establishes a comprehensive native menu system for the Tauri application, bringing it to parity with the Electron implementation and enabling full keyboard shortcut support.

## Key Features Added

**Native Menu System:**
- Complete menu bar with File, Edit, View, and Window menus
- Platform-specific adaptations (macOS app menu, Windows/Linux quit behavior)
- Full menu event handling system with proper window management

**Keyboard Accelerators:**
- CmdOrCtrl+N for New Instance creation
- Standard Edit menu shortcuts (Undo, Redo, Cut, Copy, Paste, Select All)
- View menu shortcuts (Reload, Force Reload, Toggle DevTools, Fullscreen)
- Built-in zoom hotkeys enabled via zoomHotkeysEnabled

**Enhanced Capabilities:**
- Added core:menu:default permission for menu management
- Added core:webview:allow-set-webview-zoom for zoom functionality
- Proper event communication between Tauri backend and frontend

**Frontend Integration:**
- Tauri event listener for menu:newInstance events
- Proper cleanup and error handling for event subscriptions
- Runtime environment detection for Tauri-specific behavior

## Technical Changes

**Backend (Rust):**
- Replaced empty menu stub with full SubmenuBuilder implementation
- Added comprehensive menu event handling with window operations
- Implemented MenuItem::with_id for accelerator support
- Added platform-specific menu construction logic

**Frontend (TypeScript):**
- Added Tauri event listener integration in main App component
- Proper lifecycle management with onMount/onCleanup
- Runtime environment detection for conditional Tauri behavior

**Configuration:**
- Enabled zoomHotkeysEnabled in tauri.conf.json for built-in zoom support
- Updated capabilities to include necessary menu and webview permissions

This implementation provides a native, platform-consistent user experience with full keyboard shortcut support, matching the functionality users expect from desktop applications.

packages/ui/src/App.tsx

@@ -1,4 +1,4 @@
-import { Component, Show, createMemo, createEffect, createSignal } from "solid-js"
+import { Component, Show, createMemo, createEffect, createSignal, onMount, onCleanup } from "solid-js"
 import { Dialog } from "@kobalte/core/dialog"
 import { Toaster } from "solid-toast"
 import AlertDialog from "./components/alert-dialog"
@@ -14,6 +14,7 @@ import { useCommands } from "./lib/hooks/use-commands"
 import { useAppLifecycle } from "./lib/hooks/use-app-lifecycle"
 import { getLogger } from "./lib/logger"
 import { initReleaseNotifications } from "./stores/releases"
+import { runtimeEnv } from "./lib/runtime-env"
 import {
   hasInstances,
   isSelectingFolder,
@@ -247,6 +248,28 @@ const App: Component = () => {
     getActiveSessionIdForInstance: activeSessionIdForInstance,
   })
 
+  // Listen for Tauri menu events
+  onMount(() => {
+    if (runtimeEnv.host === "tauri") {
+      const tauriBridge = (window as { __TAURI__?: { event?: { listen: (event: string, handler: (event: { payload: unknown }) => void) => Promise<() => void> } } }).__TAURI__
+      if (tauriBridge?.event) {
+        let unlistenMenu: (() => void) | null = null
+        
+        tauriBridge.event.listen("menu:newInstance", () => {
+          handleNewInstanceRequest()
+        }).then((unlisten) => {
+          unlistenMenu = unlisten
+        }).catch((error) => {
+          log.error("Failed to listen for menu:newInstance event", error)
+        })
+
+        onCleanup(() => {
+          unlistenMenu?.()
+        })
+      }
+    }
+  })
+
   return (
     <>
       <InstanceDisconnectedModal