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>

autonomous_agent_demo.py

@@ -16,6 +16,9 @@ Example Usage:
 
     # Limit iterations for testing
     python autonomous_agent_demo.py --project-dir my-app --max-iterations 5
+
+    # YOLO mode: rapid prototyping without browser testing
+    python autonomous_agent_demo.py --project-dir my-app --yolo
 """
 
 import argparse
@@ -57,6 +60,9 @@ Examples:
   # Limit iterations for testing
   python autonomous_agent_demo.py --project-dir my-app --max-iterations 5
 
+  # YOLO mode: rapid prototyping without browser testing
+  python autonomous_agent_demo.py --project-dir my-app --yolo
+
 Authentication:
   Uses Claude CLI credentials from ~/.claude/.credentials.json
   Run 'claude login' to authenticate (handled by start.bat/start.sh)
@@ -84,6 +90,13 @@ Authentication:
         help=f"Claude model to use (default: {DEFAULT_MODEL})",
     )
 
+    parser.add_argument(
+        "--yolo",
+        action="store_true",
+        default=False,
+        help="Enable YOLO mode: rapid prototyping without browser testing",
+    )
+
     return parser.parse_args()
 
 
@@ -122,6 +135,7 @@ def main() -> None:
                 project_dir=project_dir,
                 model=args.model,
                 max_iterations=args.max_iterations,
+                yolo_mode=args.yolo,
             )
         )
     except KeyboardInterrupt: