feat: Add YOLO mode for rapid prototyping without browser testing

Add a new YOLO (You Only Live Once) mode that skips all browser testing
and regression tests for faster feature iteration during prototyping.

Changes made:

**Core YOLO Mode Implementation:**
- Add --yolo CLI flag to autonomous_agent_demo.py
- Update agent.py to accept yolo_mode parameter and select appropriate prompt
- Modify client.py to conditionally include Playwright MCP server (excluded in YOLO mode)
- Add coding_prompt_yolo.template.md with static analysis only verification
- Add get_coding_prompt_yolo() to prompts.py

**Server/API Updates:**
- Add AgentStartRequest schema with yolo_mode field
- Update AgentStatus to include yolo_mode
- Modify process_manager.py to pass --yolo flag to subprocess
- Update agent router to accept yolo_mode in start request

**UI Updates:**
- Add YOLO toggle button (lightning bolt icon) in AgentControl
- Show YOLO mode indicator when agent is running in YOLO mode
- Add useAgentStatus hook to track current mode
- Update startAgent API to accept yoloMode parameter
- Add YOLO toggle in SpecCreationChat completion flow

**Spec Creation Improvements:**
- Fix create-spec.md to properly replace [FEATURE_COUNT] placeholder
- Add REQUIRED FEATURE COUNT section to initializer_prompt.template.md
- Fix spec_chat_session.py to create security settings file for Claude SDK
- Delete app_spec.txt before spec creation to allow fresh creation

**Documentation:**
- Add YOLO mode section to CLAUDE.md with usage examples
- Add checkpoint.md slash command for creating detailed commits

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

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

ui/src/components/NewProjectModal.tsx

@@ -39,6 +39,7 @@ export function NewProjectModal({
   const [error, setError] = useState<string | null>(null)
   const [initializerStatus, setInitializerStatus] = useState<InitializerStatus>('idle')
   const [initializerError, setInitializerError] = useState<string | null>(null)
+  const [yoloModeSelected, setYoloModeSelected] = useState(false)
 
   // Suppress unused variable warning - specMethod may be used in future
   void _specMethod
@@ -116,11 +117,13 @@ export function NewProjectModal({
     }
   }
 
-  const handleSpecComplete = async () => {
+  const handleSpecComplete = async (_specPath: string, yoloMode: boolean = false) => {
+    // Save yoloMode for retry
+    setYoloModeSelected(yoloMode)
     // Auto-start the initializer agent
     setInitializerStatus('starting')
     try {
-      await startAgent(projectName.trim())
+      await startAgent(projectName.trim(), yoloMode)
       // Success - navigate to project
       setStep('complete')
       setTimeout(() => {
@@ -136,7 +139,7 @@ export function NewProjectModal({
   const handleRetryInitializer = () => {
     setInitializerError(null)
     setInitializerStatus('idle')
-    handleSpecComplete()
+    handleSpecComplete('', yoloModeSelected)
   }
 
   const handleChatCancel = () => {
@@ -153,6 +156,7 @@ export function NewProjectModal({
     setError(null)
     setInitializerStatus('idle')
     setInitializerError(null)
+    setYoloModeSelected(false)
     onClose()
   }