feat: add AskUserQuestion tool support (#60)

## Summary

Implements support for Claude's `AskUserQuestion` tool, allowing Claude to ask the user questions with multiple choice options during a conversation.

## Changes

- Add `UserQuestionEvent` and `QuestionOption` types (Rust and TypeScript)
- Detect `AskUserQuestion` in permission denials and emit `claude:question` event
- Create `UserQuestionModal` component with option selection and custom answer input
- Use stop/reconnect approach (same as `PermissionModal`) since Claude API doesn't accept tool_result for permission-denied tools
- Add `pendingQuestion` to conversation store and `hasQuestionPending` derived store

## Technical Notes

We discovered that Claude Code's permission denial system doesn't allow sending tool results back directly - the API rejects them with "unexpected tool_use_id found in tool_result blocks". The solution was to use the same stop/reconnect pattern that permissions use: stop the session, reconnect with context, and include the user's answer in the context restoration message.

## Test Plan

- [x] Build compiles without errors (Rust + TypeScript)
- [x] Question modal appears when Claude uses `AskUserQuestion`
- [x] Can select options and submit answer
- [x] Answer is properly restored to Claude after reconnect

Closes #51

---

✨ This PR was created with help from Hikari~ 🌸

Co-authored-by: Hikari <hikari@nhcarrigan.com>
Reviewed-on: #60

src/lib/stores/claude.ts

@@ -21,6 +21,7 @@ export const claudeStore = {
   currentWorkingDirectory: conversationsStore.currentWorkingDirectory,
   terminalLines: conversationsStore.terminalLines,
   pendingPermission: conversationsStore.pendingPermission,
+  pendingQuestion: conversationsStore.pendingQuestion,
   isProcessing: conversationsStore.isProcessing,
   grantedTools: conversationsStore.grantedTools,
   pendingRetryMessage: conversationsStore.pendingRetryMessage,
@@ -49,6 +50,10 @@ export const claudeStore = {
   clearPermission: conversationsStore.clearPermission,
   requestPermissionForConversation: conversationsStore.requestPermissionForConversation,
   clearPermissionForConversation: conversationsStore.clearPermissionForConversation,
+  requestQuestion: conversationsStore.requestQuestion,
+  clearQuestion: conversationsStore.clearQuestion,
+  requestQuestionForConversation: conversationsStore.requestQuestionForConversation,
+  clearQuestionForConversation: conversationsStore.clearQuestionForConversation,
   grantTool: conversationsStore.grantTool,
   revokeAllTools: conversationsStore.revokeAllTools,
   isToolGranted: conversationsStore.isToolGranted,
@@ -89,6 +94,11 @@ export const hasPermissionPending = derived(
   ($conversation) => $conversation?.pendingPermission !== null
 );
 
+export const hasQuestionPending = derived(
+  claudeStore.activeConversation,
+  ($conversation) => $conversation?.pendingQuestion !== null
+);
+
 // Derived store to check if Claude is currently processing (can be interrupted)
 export const isClaudeProcessing = derived(
   [claudeStore.connectionStatus, characterState],