feat: add script-based rule evaluation with -s/--script flag

Adds support for custom request evaluation via external scripts as an alternative to regex rules.

Features:
- New -s/--script flag accepts a program path or inline command
- Scripts receive request data via environment variables (HTTPJAIL_URL, HTTPJAIL_METHOD, HTTPJAIL_HOST, HTTPJAIL_SCHEME, HTTPJAIL_PATH)
- Exit code 0 allows requests, non-zero blocks them
- Script stdout becomes additional context in 403 responses
- Inline scripts with spaces are executed via default shell

Architecture:
- Refactored rules system into trait-based architecture in src/rules/
- PatternRuleEngine for existing regex rules (src/rules/pattern.rs)
- ScriptRuleEngine for new script evaluation (src/rules/script.rs)
- Unified logging via LoggingRuleEngine wrapper
- Enhanced 403 responses to include evaluation context

Breaking changes:
- Removed unimplemented --interactive flag
- -r/--rule and -s/--script options are mutually exclusive

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

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

Author: ammario

Cargo.lock

@@ -41,6 +41,7 @@ tls-parser = "0.12.2"
 camino = "1.1.11"
 filetime = "0.2"
 ctrlc = "3.4"
+url = "2.5"
 
 [target.'cfg(target_os = "macos")'.dependencies]
 nix = { version = "0.27", features = ["user"] }