fix fork menu allowing user to double select an entry (#6430)

in cases where forking a session was not immediate due to extensions
slowing down teardown, it's possible for the user to select the
message to fork more than once and then create multiple session forks.

in this fix we close the forking menu before starting the fork process
to not allow such behavior.

fixes #6321

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

@@ -4493,19 +4493,17 @@ export class InteractiveMode {
 			const selector = new UserMessageSelectorComponent(
 				userMessages.map((m) => ({ id: m.entryId, text: m.text })),
 				async (entryId) => {
+					done();
 					try {
 						const result = await this.runtimeHost.fork(entryId);
 						if (result.cancelled) {
-							done();
 							this.ui.requestRender();
 							return;
 						}
 
 						this.editor.setText(result.selectedText ?? "");
-						done();
 						this.showStatus("Forked to new session");
 					} catch (error: unknown) {
-						done();
 						this.showError(error instanceof Error ? error.message : String(error));
 					}
 				},