bundle git via dugite-native (D-59)

macOS sandbox blocks Homebrew git execution (symlinks resolve to Cellar
paths that SBPL cannot match). Bundled dugite-native — the same
relocatable Git distribution GitHub Desktop ships.

make dugite-fetch downloads the platform tarball to native/dugite/.
Toolchain checks the bundled binary first, sets GIT_EXEC_PATH and
GIT_TEMPLATE_DIR automatically. native/dugite/ is gitignored (57 MB
compressed).

Decision D-59 in tooling.md, dependency entry in licenses.yaml
(GPL-2.0 for the git binary, MIT for dugite-native build scripts).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

macos/Runner/AppDelegate.swift

@@ -10,4 +10,59 @@ class AppDelegate: FlutterAppDelegate {
   override func applicationSupportsSecureRestorableState(_ app: NSApplication) -> Bool {
     return true
   }
+
+  override func applicationDidFinishLaunching(_ notification: Notification) {
+    guard let window = NSApp.mainWindow ?? NSApp.windows.first,
+          let flutterVC = window.contentViewController as? FlutterViewController else {
+      return
+    }
+
+    let channel = FlutterMethodChannel(
+      name: "clide/window",
+      binaryMessenger: flutterVC.engine.binaryMessenger)
+
+    channel.setMethodCallHandler { (call, result) in
+      guard let window = NSApp.mainWindow ?? NSApp.windows.first else {
+        result(FlutterMethodNotImplemented)
+        return
+      }
+      switch call.method {
+      case "pickDirectory":
+        let panel = NSOpenPanel()
+        panel.canChooseFiles = false
+        panel.canChooseDirectories = true
+        panel.allowsMultipleSelection = false
+        panel.canCreateDirectories = false
+        panel.prompt = "Open"
+        panel.message = "Select a project folder"
+        panel.beginSheetModal(for: window) { response in
+          if response == .OK, let url = panel.url {
+            result(url.path)
+          } else {
+            result(nil)
+          }
+        }
+      case "startDrag":
+        if let event = NSApp.currentEvent {
+          window.performDrag(with: event)
+        }
+        result(nil)
+      case "minimize":
+        window.miniaturize(nil)
+        result(nil)
+      case "maximize":
+        window.zoom(nil)
+        result(nil)
+      case "close":
+        window.close()
+        result(nil)
+      case "isMaximized":
+        result(window.isZoomed)
+      case "startResize":
+        result(nil)
+      default:
+        result(FlutterMethodNotImplemented)
+      }
+    }
+  }
 }