feat: Add auto-approval for mode switching

Implements automatic approval for mode switching operations when enabled, following
existing auto-approval patterns in the codebase.

Implementation:
- Added `alwaysAllowModeSwitch` to state management
- Updated `isAutoApproved` function in ChatView to handle mode switch requests
- Added mode switch option to AutoApproveMenu with appropriate handler
- Integrated with existing auto-approval flow

Tests:
- Added three test cases in ChatView.auto-approve.test.tsx:
  1. Verifies mode switch auto-approval when enabled
  2. Verifies no auto-approval when mode switch setting is disabled
  3. Verifies no auto-approval when global auto-approval is disabled

The implementation follows existing patterns for other auto-approve features
(read, write, browser, etc.) to maintain consistency in the codebase.

webview-ui/src/context/ExtensionStateContext.tsx

@@ -33,6 +33,7 @@ export interface ExtensionStateContextType extends ExtensionState {
 	setAlwaysAllowExecute: (value: boolean) => void
 	setAlwaysAllowBrowser: (value: boolean) => void
 	setAlwaysAllowMcp: (value: boolean) => void
+	setAlwaysAllowModeSwitch: (value: boolean) => void
 	setShowAnnouncement: (value: boolean) => void
 	setAllowedCommands: (value: string[]) => void
 	setSoundEnabled: (value: boolean) => void
@@ -253,6 +254,7 @@ export const ExtensionStateContextProvider: React.FC<{ children: React.ReactNode
 		setAlwaysAllowExecute: (value) => setState((prevState) => ({ ...prevState, alwaysAllowExecute: value })),
 		setAlwaysAllowBrowser: (value) => setState((prevState) => ({ ...prevState, alwaysAllowBrowser: value })),
 		setAlwaysAllowMcp: (value) => setState((prevState) => ({ ...prevState, alwaysAllowMcp: value })),
+		setAlwaysAllowModeSwitch: (value) => setState((prevState) => ({ ...prevState, alwaysAllowModeSwitch: value })),
 		setShowAnnouncement: (value) => setState((prevState) => ({ ...prevState, shouldShowAnnouncement: value })),
 		setAllowedCommands: (value) => setState((prevState) => ({ ...prevState, allowedCommands: value })),
 		setSoundEnabled: (value) => setState((prevState) => ({ ...prevState, soundEnabled: value })),