v0.7.1 - Post-v0.7.0 Enterprise Security Hardening

Highlights of v0.7.1

• Pure Python Schema Validation: Added deterministic stdlib JSON schema validation before RBAC evaluation.
• Authorization Modes: Enforced strict/production_secure/compatibility/permissive policy modes.
• Streaming Secret Guard: Added rolling buffer for cross-chunk secret detection and redacted sensitive tokens in exceptions.
• Context Propagation: Thread-safe ContextVar authorization propagation across async tasks and MCP gateways.
• SSRF Hardening: Pure-Python IP normalization (hex, decimal int, IPv6 mapped) and pre-resolution DNS rebinding defense.
• SVG Multi-Modal Security: Hardened XML ElementTree parser neutralizing entity expansion, script handlers, and dangerous schemes.
• Resource Roots: Strict path containment enforcing resource_roots boundary limits on file tools.
• Atomic Threat Intel: ReDoS-safe regex length constraints and all-or-nothing rollback for threat signature feeds.
• Zero External Runtime Dependencies: 100% standard library compliance with sub-millisecond inspection latency.