Announcing Firewall Rules

Introduced Firewall Rules, a new feature allowing customers to create fine-grained control over incoming requests by combining multiple attributes (e.g., IP, User-Agent, URI path) using a Wireshark-inspired expression language. This provides flexibility for both positive and negative security models, including pattern matching with regular expressions and a new `allow` action. The feature includes a Visual Rule Builder and Expression Editor for configuration, and introduces the `cf.client.bot` field for identifying known good bots.