docs: comprehensive README and CHANGELOG update for v0.4.5

- Update README with current project status and quality metrics
  - Add unsafe code documentation coverage (100%, 40+ SAFETY comments)
  - Update Code Quality Metrics section with unsafe docs metric
  - Enhance Implementation Security section with audit details
  - Add Gitleaks to security scanning infrastructure
  - Update bottom status line with unsafe docs coverage

- Add CHANGELOG entry for P0 critical security hardening
  - Document complete unsafe code audit across all crates
  - Detail unsafe impl Send/Sync documentation (Umem, AfXdpSocket, XdpProgram)
  - List SAFETY comments breakdown by crate (40+ total)
  - Document security scanning infrastructure (Gitleaks configuration)
  - Note 100% unsafe code documentation coverage achievement

- Reflect Phase 5 readiness with zero blocking items
- Maintain accurate quality metrics (Grade A, 92/100, 14% debt)
- Document comprehensive security hardening completion

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

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

Author: doublegate

CHANGELOG.md

@@ -9,6 +9,32 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+**P0 Critical Security Hardening (2025-11-30):**
+- Complete `unsafe` code documentation audit across all crates
+- Documented all `unsafe impl Send/Sync` implementations:
+  - `wraith-transport::Umem` - SAFETY: Single owner, no shared mutable access
+  - `wraith-transport::AfXdpSocket` - SAFETY: Atomic operations ensure thread safety
+  - `wraith-xdp::XdpProgram` - SAFETY: No concurrent access, immutable after load
+- Added comprehensive SAFETY comments to 40+ unsafe blocks
+  - `wraith-transport::af_xdp.rs` - 22 SAFETY comments (UMEM, ring ops, packet data access)
+  - `wraith-transport::numa.rs` - 9 SAFETY comments (mbind, topology detection)
+  - `wraith-transport::worker.rs` - 5 SAFETY comments (CPU affinity, core pinning)
+  - `wraith-files::io_uring_impl.rs` - 4 SAFETY comments (io_uring operations)
+- 100% unsafe code documentation coverage achieved
+- All unsafe code now has:
+  - Detailed justification explaining why unsafe is necessary
+  - Safety invariants documented
+  - Precondition requirements stated
+  - Thread safety analysis where applicable
+
+**Security Scanning Infrastructure:**
+- Added `.gitleaks.toml` configuration for false positive suppression
+  - Test vectors allowlist (BLAKE3, XChaCha20-Poly1305, X25519, Ed25519)
+  - Documentation examples allowlist (key formats, protocol examples)
+  - Zero real security findings after allowlist application
+- Gitleaks integrated into security scanning workflow
+- All security gates passing (CodeQL, cargo-audit, gitleaks)
+
 **Pre-Phase 5 Technical Debt Review (2025-11-30):**
 - Comprehensive pre-Phase 5 technical debt review (3 files, 753 insertions)
 - `to-dos/technical-debt/pre-phase-5-review-summary.md` - Executive summary of readiness assessment

README.md

@@ -34,6 +34,7 @@ WRAITH Protocol has completed Phases 1-4, delivering a fully functional core pro
 - **Test Coverage:** 607 tests passing (100% pass rate)
 - **Security Vulnerabilities:** Zero
 - **Clippy Warnings:** Zero
+- **Unsafe Code Documentation:** 100% coverage (40+ SAFETY comments)
 - **Documentation:** Comprehensive technical debt tracking (6 files in `to-dos/technical-debt/`)
 
 **Implementation Status:**
@@ -97,7 +98,7 @@ WRAITH Protocol has completed Phases 1-4, delivering a fully functional core pro
 - **Automatic Rekey**: Configurable thresholds (90% default) for time, packets, and bytes
 - **Constant-Time Operations**: All cryptographic operations timing side-channel resistant
 - **Memory Safety**: Pure Rust implementation with ZeroizeOnDrop on all secret key material
-- **Zero Unsafe Code**: No unsafe blocks in cryptographic paths
+- **Documented Unsafe Code**: Zero unsafe in crypto paths; performance-critical unsafe fully documented with SAFETY comments
 
 ### Privacy & Obfuscation
 
@@ -486,6 +487,7 @@ WRAITH Protocol uses comprehensive automated workflows for quality assurance and
 - **Dependabot:** Automated dependency updates with security prioritization
 - **CodeQL:** Static analysis for security vulnerabilities
 - **cargo-audit:** RustSec advisory database scanning
+- **Gitleaks:** Secret scanning with false positive suppression
 - **Weekly Scans:** Automated security checks every Monday
 
 ### Release Automation
@@ -535,6 +537,10 @@ WRAITH Protocol is designed with security as a core principle:
 - **Constant-Time Operations:** Side-channel resistant implementations for all critical paths
 - **SIMD Acceleration:** SSE2/NEON optimized frame parsing with security validation
 - **Buffer Pools:** Pre-allocated buffers reduce allocation overhead without compromising security
+- **Unsafe Code Audit:** 100% documentation coverage with SAFETY comments on all 40+ unsafe blocks
+  - All `unsafe impl Send/Sync` implementations documented and justified
+  - Thread safety analysis for kernel bypass operations
+  - Safety invariants documented for UMEM, io_uring, CPU affinity operations
 
 **Validation:**
 - **Test Coverage:** 607 tests covering security-critical paths (110 increase from Phase 4)
@@ -645,4 +651,4 @@ WRAITH Protocol builds on the work of many excellent projects and technologies:
 
 **WRAITH Protocol** - *Secure. Fast. Invisible.*
 
-**Status:** Phase 4 Complete (v0.4.5), Phase 5 Ready ✅ | **License:** MIT | **Language:** Rust 2024 | **Tests:** 607 | **Quality:** Grade A (92/100), 14% debt ratio, zero blocking items
+**Status:** Phase 4 Complete (v0.4.5), Phase 5 Ready ✅ | **License:** MIT | **Language:** Rust 2024 | **Tests:** 607 | **Quality:** Grade A (92/100), 14% debt ratio, 100% unsafe docs, zero blocking items