Add Ctrl+D to exit when editor is empty

- Add isCtrlD helper to keys.ts
- CustomEditor intercepts Ctrl+D and only triggers callback when editor is empty
- Single Ctrl+D with empty input exits immediately
- Update CHANGELOG to frame as feature (Kitty protocol support) not fix

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -562,6 +562,7 @@ export class InteractiveMode {
 		};
 
 		this.editor.onCtrlC = () => this.handleCtrlC();
+		this.editor.onCtrlD = () => this.handleCtrlD();
 		this.editor.onShiftTab = () => this.cycleThinkingLevel();
 		this.editor.onCtrlP = () => this.cycleModel();
 		this.editor.onCtrlO = () => this.toggleToolOutputExpansion();
@@ -1128,6 +1129,12 @@ export class InteractiveMode {
 		}
 	}
 
+	private handleCtrlD(): void {
+		// Only called when editor is empty (enforced by CustomEditor)
+		this.stop();
+		process.exit(0);
+	}
+
 	private updateEditorBorderColor(): void {
 		if (this.isBashMode) {
 			this.editor.borderColor = theme.getBashModeBorderColor();