This PR introduces several enhancements to improve user experience, automation capabilities, and benchmark insights.

🆕 New Features

Update Check (UPDATE_CHECK)

• Notifies users when a newer version of diskmark is available
• Compares current version against latest GitHub release at startup
• Controlled via UPDATE_CHECK=0|1 (default: 1)
• Automatically disabled when using machine-readable output formats

Machine-Readable Output (FORMAT)

• New FORMAT environment variable supports json, yaml, and xml output
• Structured output with configuration and results objects
• Enables easy integration with CI/CD pipelines and monitoring tools
• Automatically disables colors, emojis, and update check for clean output

Latency Metrics

• Adds average latency (in milliseconds) to each benchmark result
• Displays as X.XXms in human-readable output
• Included as latency_ms field in structured outputs
• Uses fio's clat_ns.mean (completion latency) for accurate measurement

Version Injection

• Docker build now injects version from Git tag into /etc/diskmark-version
• Enables accurate version display and update checking

🔧 Improvements

CI/CD

• Added GitHub badges to README (tag, CodeQL, Tests, Docker Image)
• Test workflow now uses continue-on-error: true pattern for per-step failure visibility
• Added comprehensive tests for UPDATE_CHECK and FORMAT validation
• Benchmark tests automatically disable update check for cleaner output

Dockerfile

• Added wget and ssl_client binaries for HTTPS update checking
• Renamed staging directory from /dist to /diskmark for clarity
• Added version file injection via build arg

📖 Documentation

• Updated parameter table with UPDATE_CHECK and FORMAT options
• Added "Machine-readable output" section with usage examples
• Added sample outputs for JSON, YAML, and XML formats (with latency)

📊 Sample Output

Human-readable:

Sequential 1M Q8T1:
<= Read:  524 MB/s, 499 IO/s, 2.15ms
=> Write: 498 MB/s, 475 IO/s, 1.89ms

JSON:

{
  "configuration": { ... },
  "results": [
    {"name": "SEQ1MQ8T1", "status": "success", 
     "read": {"bandwidth_mb": 524, "iops": 499, "latency_ms": 2.15},
     "write": {"bandwidth_mb": 498, "iops": 475, "latency_ms": 1.89}}
  ]
}

✅ Testing

• All existing tests pass
• New validation tests for UPDATE_CHECK (valid/invalid values)
• New validation tests for FORMAT (valid/invalid values)
• FORMAT output validation tests (JSON/YAML/XML validity and structure)
• Image size unchanged (~36MB)

🔄 Breaking Changes

None. All new features are opt-in or backward compatible.