feat: migrate browser automation from Playwright MCP to CLI, fix headless setting

Major changes across 21 files (755 additions, 196 deletions):

Browser Automation Migration:
- Add versioned project migration system (prompts.py) with content-based
  detection and section-level regex replacement for coding/testing prompts
- Migrate STEP 5 (browser verification) and BROWSER AUTOMATION sections
  in coding prompt template to use playwright-cli commands
- Migrate STEP 2 and AVAILABLE TOOLS sections in testing prompt template
- Migration auto-runs at agent startup (autonomous_agent_demo.py), copies
  playwright-cli skill, scaffolds .playwright/cli.config.json, updates
  .gitignore, and stamps .migration_version file
- Add playwright-cli command validation to security allowlist (security.py)
  with tests for allowed subcommands and blocked eval/run-code

Headless Browser Setting Fix:
- Add _apply_playwright_headless() to process_manager.py that reads/updates
  .playwright/cli.config.json before agent subprocess launch
- Remove dead PLAYWRIGHT_HEADLESS env var that was never consumed
- Settings UI toggle now correctly controls visible browser window

Playwright CLI Auto-Install:
- Add ensurePlaywrightCli() to lib/cli.js for npm global entry point
- Add playwright-cli detection + npm install to start.bat, start.sh,
  start_ui.bat, start_ui.sh for all startup paths

Other Improvements:
- Add project folder path tooltip to ProjectSelector.tsx dropdown items
- Remove legacy Playwright MCP server configuration from client.py
- Update CLAUDE.md with playwright-cli skill documentation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/services/process_manager.py

@@ -227,6 +227,28 @@ class AgentProcessManager:
         """Remove lock file."""
         self.lock_file.unlink(missing_ok=True)
 
+    def _apply_playwright_headless(self, headless: bool) -> None:
+        """Update .playwright/cli.config.json with the current headless setting.
+
+        playwright-cli reads this config file on each ``open`` command, so
+        updating it before the agent starts is sufficient.
+        """
+        config_file = self.project_dir / ".playwright" / "cli.config.json"
+        if not config_file.exists():
+            return
+        try:
+            import json
+            config = json.loads(config_file.read_text(encoding="utf-8"))
+            launch_opts = config.get("browser", {}).get("launchOptions", {})
+            if launch_opts.get("headless") == headless:
+                return  # already correct
+            launch_opts["headless"] = headless
+            config.setdefault("browser", {})["launchOptions"] = launch_opts
+            config_file.write_text(json.dumps(config, indent=2) + "\n", encoding="utf-8")
+            logger.info("Set playwright headless=%s for %s", headless, self.project_name)
+        except Exception:
+            logger.warning("Failed to update playwright config", exc_info=True)
+
     def _cleanup_stale_features(self) -> None:
         """Clear in_progress flag for all features when agent stops/crashes.
 
@@ -361,6 +383,15 @@ class AgentProcessManager:
         if not self._check_lock():
             return False, "Another agent instance is already running for this project"
 
+        # Clean up stale browser daemons from previous runs
+        try:
+            subprocess.run(
+                ["playwright-cli", "kill-all"],
+                timeout=5, capture_output=True,
+            )
+        except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
+            pass
+
         # Clean up features stuck from a previous crash/stop
         self._cleanup_stale_features()
 
@@ -397,6 +428,10 @@ class AgentProcessManager:
         # Add --batch-size flag for multi-feature batching
         cmd.extend(["--batch-size", str(batch_size)])
 
+        # Apply headless setting to .playwright/cli.config.json so playwright-cli
+        # picks it up (the only mechanism it supports for headless control)
+        self._apply_playwright_headless(playwright_headless)
+
         try:
             # Start subprocess with piped stdout/stderr
             # Use project_dir as cwd so Claude SDK sandbox allows access to project files
@@ -409,7 +444,7 @@ class AgentProcessManager:
             subprocess_env = {
                 **os.environ,
                 "PYTHONUNBUFFERED": "1",
-                "PLAYWRIGHT_HEADLESS": "true" if playwright_headless else "false",
+                "PLAYWRIGHT_CLI_SESSION": f"agent-{self.project_name}-{os.getpid()}",
                 "NODE_COMPILE_CACHE": "",  # Disable V8 compile caching to prevent .node file accumulation in %TEMP%
                 **api_env,
             }
@@ -469,6 +504,15 @@ class AgentProcessManager:
                 except asyncio.CancelledError:
                     pass
 
+            # Kill browser daemons before stopping agent
+            try:
+                subprocess.run(
+                    ["playwright-cli", "kill-all"],
+                    timeout=5, capture_output=True,
+                )
+            except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
+                pass
+
             # CRITICAL: Kill entire process tree, not just orchestrator
             # This ensures all spawned coding/testing agents are also terminated
             proc = self.process  # Capture reference before async call