fix: coverage timeout

[wasabeef]

Description

Fixes CI coverage generation timeout issues by improving cargo-tarpaulin configuration.

Changes

• Increased timeout from 180s to 300s
• Added --engine llvm for stability
• Excluded test files from coverage calculation
• Added error handling to prevent CI failures
• Coverage now reports source code only (more accurate)

Impact

• CI stability improved
• Coverage metrics more accurate (14.6% vs 17%)
• Build failures prevented when tarpaulin encounters issues

[github-actions]

📊 CI Results

✅ All Checks Passed

📋 Coverage & Testing

• Coverage: 14.6%
• Total Tests: 248
• Security Tests: 55
• Performance Tests: 17
• MockDeviceManager Tests: 21

🎯 Quality Metrics

⚠️ Coverage: 14.6%
✅ Linting: All clippy warnings resolved
✅ Formatting: Code properly formatted
✅ Security: Comprehensive protection validated

🚀 Build Status

• Ubuntu: ✅ Passed
• macOS: ✅ Passed
• Artifacts: ✅ Generated

🧪 Test Suite Innovation

• Test Files: 49 total (5 MockDeviceManager)
• Emulator Independent: ✅ 21 tests (< 6 seconds)
• Mock Coverage: 10% of test files are emulator-independent
• CI Performance: Fast feedback with MockDeviceManager integration