Phase 115.4: Comprehensive Undefined Behavior Analysis

Added comprehensive UB analysis covering 6 major categories:
- Uninitialized variables: 3 low-risk issues (code smells only)
- Pointer arithmetic: 10+ issues (2 HIGH, 5 MEDIUM, 3+ LOW)
- Null pointer dereferences: ZERO issues (excellent safety)
- Integer overflow: 12 issues (3 CRITICAL, 4 HIGH, 3 MEDIUM, 2 LOW)
- Type punning/aliasing: 8 issues (2 HIGH, 4 MEDIUM, 2 LOW)
- Shift operations: 7 issues (2 MEDIUM, 5 LOW)

Total: 40+ UB patterns identified across 84 files (~35K LOC)

Critical issues requiring immediate attention:
- Hash table length doubling without overflow check
- Power-of-two shift operations with potential UB
- Table array reallocation unchecked pointer arithmetic
- GC-triggered pointer invalidation in string concat
- Stack restore char* round-trip (LTO risk)

Proposed action plan: Phases 116-119 (10-13 days)
- Phase 116: Fix 11 critical/high issues
- Phase 117: Fix remaining high-priority issues
- Phase 118: Medium priority + comprehensive hardening
- Phase 119: Testing, validation, documentation

Document includes:
- Detailed analysis of each issue with file:line references
- Risk assessments and severity classifications
- Code examples and reproduction scenarios
- Specific fix recommendations with estimated time
- Prioritized action plan with deliverables
- Systemic improvement recommendations

Status: NOT PRODUCTION READY - Critical fixes required

Author: claude