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>

temp_cleanup.py

@@ -125,14 +125,18 @@ def cleanup_stale_temp(max_age_seconds: int = MAX_AGE_SECONDS) -> dict:
 
 def cleanup_project_screenshots(project_dir: Path, max_age_seconds: int = 300) -> dict:
     """
-    Clean up stale screenshot files from the project root.
+    Clean up stale Playwright CLI artifacts from the project.
 
-    Playwright browser verification can leave .png files in the project
-    directory. This removes them after they've aged out (default 5 minutes).
+    The Playwright CLI daemon saves screenshots, snapshots, and other artifacts
+    to `{project_dir}/.playwright-cli/`. This removes them after they've aged
+    out (default 5 minutes).
+
+    Also cleans up legacy screenshot patterns from the project root (from the
+    old Playwright MCP server approach).
 
     Args:
         project_dir: Path to the project directory.
-        max_age_seconds: Maximum age in seconds before a screenshot is deleted.
+        max_age_seconds: Maximum age in seconds before an artifact is deleted.
                         Defaults to 5 minutes (300 seconds).
 
     Returns:
@@ -141,13 +145,33 @@ def cleanup_project_screenshots(project_dir: Path, max_age_seconds: int = 300) -
     cutoff_time = time.time() - max_age_seconds
     stats: dict = {"files_deleted": 0, "bytes_freed": 0, "errors": []}
 
-    screenshot_patterns = [
+    # Clean up .playwright-cli/ directory (new CLI approach)
+    playwright_cli_dir = project_dir / ".playwright-cli"
+    if playwright_cli_dir.exists():
+        for item in playwright_cli_dir.iterdir():
+            if not item.is_file():
+                continue
+            try:
+                mtime = item.stat().st_mtime
+                if mtime < cutoff_time:
+                    size = item.stat().st_size
+                    item.unlink(missing_ok=True)
+                    if not item.exists():
+                        stats["files_deleted"] += 1
+                        stats["bytes_freed"] += size
+                        logger.debug(f"Deleted playwright-cli artifact: {item}")
+            except Exception as e:
+                stats["errors"].append(f"Failed to delete {item}: {e}")
+                logger.debug(f"Failed to delete artifact {item}: {e}")
+
+    # Legacy cleanup: root-level screenshot patterns (from old MCP server approach)
+    legacy_patterns = [
         "feature*-*.png",
         "screenshot-*.png",
         "step-*.png",
     ]
 
-    for pattern in screenshot_patterns:
+    for pattern in legacy_patterns:
         for item in project_dir.glob(pattern):
             if not item.is_file():
                 continue
@@ -159,14 +183,14 @@ def cleanup_project_screenshots(project_dir: Path, max_age_seconds: int = 300) -
                     if not item.exists():
                         stats["files_deleted"] += 1
                         stats["bytes_freed"] += size
-                        logger.debug(f"Deleted project screenshot: {item}")
+                        logger.debug(f"Deleted legacy screenshot: {item}")
             except Exception as e:
                 stats["errors"].append(f"Failed to delete {item}: {e}")
                 logger.debug(f"Failed to delete screenshot {item}: {e}")
 
     if stats["files_deleted"] > 0:
         mb_freed = stats["bytes_freed"] / (1024 * 1024)
-        logger.info(f"Screenshot cleanup: {stats['files_deleted']} files, {mb_freed:.1f} MB freed")
+        logger.info(f"Artifact cleanup: {stats['files_deleted']} files, {mb_freed:.1f} MB freed")
 
     return stats