feat(extension): auto-close automation window after command completes

- Add 'close-window' action to extension protocol and background.ts
- Add Page.closeWindow() method to send close-window command
- browserSession() now closes automation window in cleanup
- Remove domain pre-navigation + 2s wait from main.ts (CDP handles
  cross-domain cookies natively, no same-origin workaround needed)
- Net effect: commands run faster, no stale windows left behind

extension/dist/background.js

@@ -219,6 +219,7 @@ async function handleCommand(cmd) {
 			case "tabs": return await handleTabs(cmd);
 			case "cookies": return await handleCookies(cmd);
 			case "screenshot": return await handleScreenshot(cmd);
+			case "close-window": return await handleCloseWindow(cmd);
 			default: return {
 				id: cmd.id,
 				ok: false,
@@ -447,4 +448,17 @@ async function handleScreenshot(cmd) {
 		};
 	}
 }
+async function handleCloseWindow(cmd) {
+	if (automationWindowId !== null) {
+		try {
+			await chrome.windows.remove(automationWindowId);
+		} catch {}
+		automationWindowId = null;
+	}
+	return {
+		id: cmd.id,
+		ok: true,
+		data: { closed: true }
+	};
+}
 //#endregion

extension/src/background.ts

@@ -165,6 +165,8 @@ async function handleCommand(cmd: Command): Promise<Result> {
         return await handleCookies(cmd);
       case 'screenshot':
         return await handleScreenshot(cmd);
+      case 'close-window':
+        return await handleCloseWindow(cmd);
       default:
         return { id: cmd.id, ok: false, error: `Unknown action: ${cmd.action}` };
     }
@@ -332,3 +334,15 @@ async function handleScreenshot(cmd: Command): Promise<Result> {
     return { id: cmd.id, ok: false, error: err instanceof Error ? err.message : String(err) };
   }
 }
+
+async function handleCloseWindow(cmd: Command): Promise<Result> {
+  if (automationWindowId !== null) {
+    try {
+      await chrome.windows.remove(automationWindowId);
+    } catch {
+      // Window may already be closed
+    }
+    automationWindowId = null;
+  }
+  return { id: cmd.id, ok: true, data: { closed: true } };
+}

extension/src/protocol.ts

@@ -5,7 +5,7 @@
  * Everything else is just JS code sent via 'exec'.
  */
 
-export type Action = 'exec' | 'navigate' | 'tabs' | 'cookies' | 'screenshot';
+export type Action = 'exec' | 'navigate' | 'tabs' | 'cookies' | 'screenshot' | 'close-window';
 
 export interface Command {
   /** Unique request ID */