fix: suppress false positive security warnings with noqa comments

- Add SEC-034 noqa comments to HTTP/HTTPS validation code
- Add SEC-041 noqa to MD5 hash used for cache keys (not crypto)
- Add {# sanitized #} comments to templates using |safe filter
- Fix validator regex to detect sanitized comments after Jinja closing tags
- Add vendor/** to ignore list for third-party libraries

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

models/database/vendor_domain.py

@@ -81,7 +81,7 @@ class VendorDomain(Base, TimestampMixin):
         - EXAMPLE.COM → example.com
         """
         # Remove protocol
-        domain = domain.replace("https://", "").replace("http://", "")
+        domain = domain.replace("https://", "").replace("http://", "")  # noqa: SEC-034
 
         # Remove trailing slash
         domain = domain.rstrip("/")