feat: Add robust fallback mechanisms for spec creation chat

Add multiple escape hatches to prevent users from getting stuck during
spec creation when the WebSocket completion signal fails.

Changes:
- Add "Exit to Project" button always visible in chat header
- Add /exit command detection to immediately exit to project
- Add backend GET /api/spec/status/{project} endpoint to poll status file
- Add getSpecStatus() API function in frontend
- Add status file polling (every 3s) in useSpecChat hook
- Update create-spec.md with status file write instructions

How it works:
1. Happy path: Claude writes .spec_status.json as final step, UI polls
   and detects completion, shows "Continue to Project" button
2. Escape hatch: User can always click "Exit to Project" or type /exit
   to instantly select the project and close modal, then manually start
   the agent from the main UI

This ensures users always have a way forward even if the WebSocket
completion detection fails due to tool call tracking issues.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ui/src/components/SpecCreationChat.tsx

@@ -6,7 +6,7 @@
  */
 
 import { useCallback, useEffect, useRef, useState } from 'react'
-import { Send, X, CheckCircle2, AlertCircle, Wifi, WifiOff, RotateCcw, Loader2, ArrowRight, Zap, Paperclip } from 'lucide-react'
+import { Send, X, CheckCircle2, AlertCircle, Wifi, WifiOff, RotateCcw, Loader2, ArrowRight, Zap, Paperclip, ExternalLink } from 'lucide-react'
 import { useSpecChat } from '../hooks/useSpecChat'
 import { ChatMessage } from './ChatMessage'
 import { QuestionOptions } from './QuestionOptions'
@@ -23,6 +23,7 @@ interface SpecCreationChatProps {
   projectName: string
   onComplete: (specPath: string, yoloMode?: boolean) => void
   onCancel: () => void
+  onExitToProject: () => void  // Exit to project without starting agent
   initializerStatus?: InitializerStatus
   initializerError?: string | null
   onRetryInitializer?: () => void
@@ -32,6 +33,7 @@ export function SpecCreationChat({
   projectName,
   onComplete,
   onCancel,
+  onExitToProject,
   initializerStatus = 'idle',
   initializerError = null,
   onRetryInitializer,
@@ -86,6 +88,13 @@ export function SpecCreationChat({
     // Allow sending if there's text OR attachments
     if ((!trimmed && pendingAttachments.length === 0) || isLoading) return
 
+    // Detect /exit command - exit to project without sending to Claude
+    if (/^\s*\/exit\s*$/i.test(trimmed)) {
+      setInput('')
+      onExitToProject()
+      return
+    }
+
     sendMessage(trimmed, pendingAttachments.length > 0 ? pendingAttachments : undefined)
     setInput('')
     setPendingAttachments([]) // Clear attachments after sending
@@ -210,6 +219,16 @@ export function SpecCreationChat({
             </span>
           )}
 
+          {/* Exit to Project - always visible escape hatch */}
+          <button
+            onClick={onExitToProject}
+            className="neo-btn neo-btn-ghost text-sm py-2"
+            title="Exit chat and go to project (you can start the agent manually)"
+          >
+            <ExternalLink size={16} />
+            Exit to Project
+          </button>
+
           <button
             onClick={onCancel}
             className="neo-btn neo-btn-ghost p-2"
@@ -347,7 +366,7 @@ export function SpecCreationChat({
                   ? 'Or type a custom response...'
                   : pendingAttachments.length > 0
                     ? 'Add a message with your image(s)...'
-                    : 'Type your response...'
+                    : 'Type your response... (or /exit to go to project)'
               }
               className="neo-input flex-1"
               disabled={(isLoading && !currentQuestions) || connectionStatus !== 'connected'}