Fix: Add comprehensive security test coverage for core.ts (Issue #29)

Summary

• Implements comprehensive security test coverage for core.ts to address critical security vulnerability (Issue #29)
• Achieves 87.69% statement coverage (up from 28%) and 100% function coverage
• Tests 31 critical security scenarios including token sanitization, input validation, and URL encoding

Test Coverage Achievements

• Statements: 87.69% (target: 80%+) ✅
• Functions: 100% (target: 80%+) ✅
• Security-Critical Functions: All covered with comprehensive edge cases

Security Test Areas Covered

🔒 Token Security & Sanitization

• Bearer token redaction from error messages
• Personal access token sanitization in logs
• Token leakage prevention in stack traces
• Environment variable security validation

🛡️ Input Validation & Sanitization

• Project ID validation and encoding
• Branch name special character handling
• File path traversal prevention
• URL encoding security

🌐 HTTP Client Security

• Request/response header sanitization
• Error message security filtering
• API URL validation and normalization
• Authentication header security

🔍 Git Repository Detection

• Repository path validation
• Remote URL parsing security
• Git configuration access control
• Directory traversal prevention

Quality Gates Status

• ✅ TypeScript compilation passes
• ✅ ESLint security rules enforced
• ✅ Prettier formatting applied
• ✅ All 31 security tests passing
• ✅ Coverage thresholds exceeded

Security Impact

This addresses a critical security vulnerability where core authentication and validation functions had insufficient test coverage (28%), leaving potential attack vectors undetected.

Files Modified:

• tests/unit/core-security.test.ts (new) - Comprehensive security test suite
• eslint.config.js (updated) - Test-specific ESLint configuration

Resolves: Issue #29 (core.ts has dangerously low 28% test coverage)

🤖 Generated with Claude Code

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