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/lib/api.ts

@@ -117,9 +117,13 @@ export async function getAgentStatus(projectName: string): Promise<AgentStatusRe
   return fetchJSON(`/projects/${encodeURIComponent(projectName)}/agent/status`)
 }
 
-export async function startAgent(projectName: string): Promise<AgentActionResponse> {
+export async function startAgent(
+  projectName: string,
+  yoloMode: boolean = false
+): Promise<AgentActionResponse> {
   return fetchJSON(`/projects/${encodeURIComponent(projectName)}/agent/start`, {
     method: 'POST',
+    body: JSON.stringify({ yolo_mode: yoloMode }),
   })
 }
 

ui/src/lib/types.ts

@@ -89,6 +89,7 @@ export interface AgentStatusResponse {
   status: AgentStatus
   pid: number | null
   started_at: string | null
+  yolo_mode: boolean
 }
 
 export interface AgentActionResponse {