Release v0.3.0

feat: enhance provider session management and usage tracking

- Introduced `utilizationPercent` and `contextWindow` to track session usage and context limits.
- Updated `rankProviders` to consider session limits and utilization when selecting providers.
- Enhanced `parseClaudeLine` and `parseCodexLine` to report usage and session information accurately.
- Improved UI to display session usage, context capacity, and provider status more clearly.
- Added new styles for usage gauges and capacity badges to reflect provider limits.
- Implemented tests for new features, ensuring accurate reporting of usage and session limits across providers.