Feat: Update Documentation to match current codebase

[cwdaniel]

Summary

• Comprehensive documentation audit covering aviation situation API, wind visualization, biological/velocity layers, and updated deployment guidance

Changes
Bug fixes:
N/A

Documentation (8 files):

• architecture.md — Added NEXRAD layers (biological/velocity), wind flow visualization, full aviation situation API section with data flow, components, and Redis keys
• api.md — Added ?layer= param on tile endpoint, GET /wind/grid endpoint, and all six situation API endpoints (summary, airport, history, route, cells, WebSocket)
• configuration.md — Added SITUATION_PORT, SAMPLING_ZOOM, AIRPORTS_OVERRIDE_PATH env vars and situation-api Docker Compose block
• sources.md — Added GFS wind data source
• palettes.md — Added biological and velocity palette docs with full color stop tables
• deployment.md — Added nginx routing for situation API paths, replaced GPU upscaler section with deprecation notice
• getting-started.md — Added radrview-situation-api container, fixed data storage to reference named Docker volumes
• README.md — Updated project description to include aviation situation API