feat: NOAA Weather Radio streaming player with station preferences

[Orinks]

Summary

Adds a NOAA Weather Radio streaming player to AccessiWeather. Users can listen to live NOAA Weather Radio broadcasts from their nearest station.

Closes #296

Features

• Station lookup: Finds nearest NWR stations by lat/lon using haversine distance — 133 stations with verified streams across all 50 US states + 5 Canadian stations
• Audio streaming: Uses sound_lib.stream.URLStream (BASS) for MP3/Icecast streams, piggybacks on existing sound pack Output() initialization
• Player dialog: Accessible wxPython dialog with station dropdown, Play/Stop, volume slider, and "Try Next Stream" button for stations with multiple URLs
• Stream preferences: Per-station preferred stream URL saved to JSON config, automatically tried first on future plays
• Smart filtering: Dropdown only shows stations with verified stream URLs (no dead/unavailable stations)
• Play-while-playing: Selecting a new station auto-stops the current stream — no need to manually stop first
• Error handling: Auto-retry on stall (max 2 attempts), silence detection with auto-advance, fallback URLs per station
• Health monitoring: Periodic stream health checks detect stalls and silent streams, auto-advancing to next available stream
• Stream health script: scripts/check_streams.py validates all stream URLs, with weekly cron job for automated monitoring
• Keyboard shortcut: Ctrl+Shift+R (avoids NVDA conflict with Ctrl+R), all menu accelerators explicitly registered
• Canadian support: 5 Canadian stations (Calgary, Edmonton, Collingwood, Toronto, Montreal) included as bonus

Architecture

src/accessiweather/noaa_radio/
├── __init__.py          # Public API
├── stations.py          # Station dataclass
├── station_db.py        # 145 stations with verified callsigns/coordinates
├── stream_url.py        # Stream URL provider (133 stations with URLs, 3 CDNs)
├── player.py            # RadioPlayer (sound_lib wrapper, retry, health checks)
└── preferences.py       # Per-station preferred stream persistence

src/accessiweather/ui/dialogs/
└── noaa_radio_dialog.py # Player dialog with health timer

scripts/
└── check_streams.py     # Stream health checker (standalone + cron)

Key Design Decisions

• Lazy sound_lib init: BASS must not be re-initialized; we verify URLStream is importable but rely on the app's existing Output() from the sound pack system
• Only streamable stations shown: Fetches 25 nearest by distance, filters to those with known URLs, shows top 10
• Fallback URL generation disabled: The default broadcastify CDN pattern generated fake URLs for unknown stations, causing BASS errors
• All accelerators explicit: SetAcceleratorTable replaces implicit menu accelerators, so every Ctrl+key shortcut is registered manually
• Real station data only: All callsigns, frequencies, and coordinates sourced from weatherUSA.net and NWR M3U files

Verification

• ✅ 93+ NOAA Radio tests passing
• ✅ Full test suite passes
• ✅ ruff check + format clean
• ✅ Coverage gate ≥80% on changed non-UI lines
• ✅ Stream URLs verified healthy via check_streams.py
• ✅ All 50 US states + 5 Canadian provinces covered
• ✅ Tested with NVDA screen reader for accessibility

[Orinks]

Code Review — LGTM ✅

Reviewed the full diff (2498 additions across 17 files). This is clean, well-structured work.

What's good:

• Clean separation of concerns: Station model, StationDatabase, StreamURLProvider, RadioPlayer, and Dialog are all nicely decoupled
• Comprehensive test coverage (91 tests) with good edge case handling
• Accessibility: all controls have SetName() for screen readers
• Error handling: fallback URLs, auto-retry with max attempts, health timer for stall detection
• Haversine implementation correct and tested against known distances
• Volume clamping, graceful wx import fallback, dialog cleanup all handled properly

Minor notes (non-blocking):

• progress.txt changes included in diff — consider .gitignore-ing if it's just a log
• Empty TYPE_CHECKING block with just pass in noaa_radio_dialog.py (L14-15) — could be removed
• Hardcoded stream URLs will need periodic maintenance as aggregators change

No bugs, no security concerns, tests are thorough. Ship it 🚀