feat: add comprehensive testing and error tracking for edit mode

Add robust testing framework to prevent regression of edit mode:
- Comprehensive regression tests for JavaScript syntax validation
- Build-time JavaScript validation tool with Node.js integration
- Enhanced error tracking with detailed logging and recovery
- Makefile integration for `make validate-js` command

Features:
- Validates JavaScript syntax in generated HTML templates
- Detects common issues like broken string literals and brace escaping
- Enhanced error reporting with timestamps and context
- Automatic error recovery for graceful degradation
- Build validation to catch syntax errors before deployment

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Makefile

@@ -83,6 +83,7 @@ help:
 	@echo "  status      - Show git status for repo and submodules"
 	@echo "  clean       - Clean build artifacts"
 	@echo "  check-deps  - Check dependency status"
+	@echo "  validate-js - Validate JavaScript syntax in templates"
 	@echo ""
 	@echo "Documentation:"
 	@echo "  update-digest   - Update ProjectStatusDigest.md (requires Claude Code)"
@@ -1340,3 +1341,13 @@ cost-help:
 	@echo "💰 Currency: Costs calculated in USD and EUR"
 	@echo "🤖 Model: Default claude-sonnet-4 pricing"
 
+# JavaScript validation for edit mode templates
+validate-js: $(VENV)/bin/activate
+	@echo "🔍 Validating JavaScript syntax in templates..."
+	@if command -v node >/dev/null 2>&1; then \
+		$(PYTHON) tools/validate_js_syntax.py; \
+	else \
+		echo "⚠️  Node.js not available - skipping JavaScript validation"; \
+		echo "   Install Node.js to enable JavaScript syntax checking"; \
+	fi
+