feat: Add comprehensive CLI options, export functionality, and TUI fi…

[parvvaresh]

…ltering

Add extensive new features to enhance monitoring, reporting, and usability:

Command-Line Interface:

• Add --interval flag for configurable sampling intervals
• Add --db flag for custom database locations
• Add --once flag for one-shot sampling mode
• Add --continuous flag for background monitoring
• Add --export flag with JSON and CSV format support
• Add --output flag to specify export destination
• Add --list-users flag for quick user summary
• Add --max-temp and --max-mem flags for alert thresholds
• Add --version flag for version information

Export & Reporting:

• Implement JSON export with full snapshot data structure
• Implement CSV export for spreadsheet compatibility
• Support output to file or stdout for piping
• Enable integration with monitoring systems and APIs

TUI Enhancements:

• Add user filtering (key: f) to focus on specific users
• Add GPU filtering (key: g) for multi-GPU systems
• Add memory sorting toggle (key: m)
• Add clear filters command (key: c)
• Display active filter indicators in header
• Show visual highlights for filtered items

Alert System:

• Add configurable temperature threshold monitoring
• Add configurable memory utilization alerts
• Display visual alerts in TUI with warning indicators
• Output alerts to stderr in continuous mode for scripting

Architecture:

• Introduce Config struct for TUI configuration
• Add NewWithConfig() constructor for advanced initialization
• Implement getFilteredSnapshot() for filter application
• Add helper functions for user enumeration and filtering
• Maintain backward compatibility with existing API

Documentation:

• Create FEATURES.md with comprehensive examples
• Create QUICKSTART.md for quick reference
• Create CHANGELOG.md tracking version history
• Update README.md with usage examples and integration guides
• Add troubleshooting section and advanced use cases

Files modified:

• cmd/gpu-tracker/main.go
• internal/tui/model.go
• internal/tui/view.go
• README.md

Files added:

• FEATURES.md
• QUICKSTART.md
• CHANGELOG.md

Breaking changes: None
Backward compatibility: Full compatibility with v1.0.x maintained

Version: 1.1.0