fix(plan-mode): change shortcut from Shift+P to Ctrl+Alt+P (#746)

Shift+P conflicts with typing capital P. Ctrl+Alt+P is cross-platform
safe and doesn't conflict with common shortcuts like:
- Ctrl+Shift+P (command palette on Windows/VS Code)
- Shift+Alt+P (types π on macOS)

packages/coding-agent/examples/extensions/plan-mode/README.md

@@ -15,7 +15,7 @@ Read-only exploration mode for safe code analysis.
 
 - `/plan` - Toggle plan mode
 - `/todos` - Show current plan progress
-- `Shift+P` - Toggle plan mode (shortcut)
+- `Ctrl+Alt+P` - Toggle plan mode (shortcut)
 
 ## Usage
 

packages/coding-agent/examples/extensions/plan-mode/index.ts

@@ -5,7 +5,7 @@
  * When enabled, only read-only tools are available.
  *
  * Features:
- * - /plan command or Shift+P to toggle
+ * - /plan command or Ctrl+Alt+P to toggle
  * - Bash restricted to allowlisted read-only commands
  * - Extracts numbered plan steps from "Plan:" sections
  * - [DONE:n] markers to complete steps during execution
@@ -113,7 +113,7 @@ export default function planModeExtension(pi: ExtensionAPI): void {
 		},
 	});
 
-	pi.registerShortcut(Key.shift("p"), {
+	pi.registerShortcut(Key.ctrlAlt("p"), {
 		description: "Toggle plan mode",
 		handler: async (ctx) => togglePlanMode(ctx),
 	});