docs: comprehensive README and architecture documentation

[NOVA-Openclaw]

Summary

Comprehensive documentation update for NOVA Security project:

README.md Rewrite

• Project Overview: Clear description of system components and deny-by-default stance
• Trust Levels: Complete table of all 6 levels with permissions and descriptions
• Roles System: RBAC with cumulative assignments, default roles, and functions
• Security Policies: Policy types, actions, evaluation priority, and examples
• Policy Collector: How it works, confidence thresholds, and usage examples
• SQL Functions Reference: , , , , etc.
• Views Reference: , ,
• Installation: Step-by-step schema application and configuration
• Usage Examples: Concrete SQL examples for common operations
• Updated Components Table: Removed reference to non-existent

ARCHITECTURE.md Creation

• System Overview: Core components and design philosophy
• Data Flow: Message processing pipeline and policy collector details
• Schema Relationships: Entity-centric security model diagram and table descriptions
• Policy Evaluation Logic: Priority-based matching algorithm
• Confidence-Based Auto-Apply: High vs low confidence handling
• Integration Points: Message handling, database, agent ecosystem
• Security Considerations: Principle of least privilege, defense in depth
• Performance Considerations: Indexing strategy and optimization

Key Improvements

• Accurate documentation of existing components (no planned features)
• Concrete SQL examples for immediate use
• Clear architecture for developers and integrators
• Removal of inaccurate component references