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>

prompts.py

@@ -75,6 +75,11 @@ def get_coding_prompt(project_dir: Path | None = None) -> str:
     return load_prompt("coding_prompt", project_dir)
 
 
+def get_coding_prompt_yolo(project_dir: Path | None = None) -> str:
+    """Load the YOLO mode coding agent prompt (project-specific if available)."""
+    return load_prompt("coding_prompt_yolo", project_dir)
+
+
 def get_app_spec(project_dir: Path) -> str:
     """
     Load the app spec from the project.
@@ -131,6 +136,7 @@ def scaffold_project_prompts(project_dir: Path) -> Path:
     templates = [
         ("app_spec.template.txt", "app_spec.txt"),
         ("coding_prompt.template.md", "coding_prompt.md"),
+        ("coding_prompt_yolo.template.md", "coding_prompt_yolo.md"),
         ("initializer_prompt.template.md", "initializer_prompt.md"),
     ]