feat: add ask_user interactive user input to frontend

Wire the sidecar user-input-requested protocol event through the main
process, IPC layer, and renderer UI so agents can ask the user
interactive questions with choices and freeform input.

- Add UserInputRequestedEvent and ResolveUserInputCommand to sidecar
  protocol types
- Add resolveUserInput method to SidecarClient and onUserInput callback
  to runTurn
- Create PendingUserInputRecord domain type and add pendingUserInput to
  SessionRecord
- Add handleUserInputRequested and resolveSessionUserInput to
  AryxAppService with handle management
- Register sessions:resolve-user-input IPC channel with preload bridge
- Create UserInputBanner component with choice buttons and freeform
  input
- Integrate UserInputBanner into ChatPane with header indicator

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tests/main/runTurnPending.test.ts

@@ -16,6 +16,7 @@ describe('run turn pending helpers', () => {
       onDelta: () => undefined,
       onActivity: () => undefined,
       onApproval: () => undefined,
+      onUserInput: () => undefined,
       errored: false,
     };
 
@@ -38,6 +39,7 @@ describe('run turn pending helpers', () => {
       onDelta: () => undefined,
       onActivity: () => undefined,
       onApproval: () => undefined,
+      onUserInput: () => undefined,
       errored: false,
     };