Add weather satellite decoder for NOAA APT and Meteor LRPT

New module for receiving and decoding weather satellite images using
SatDump CLI. Supports NOAA-15/18/19 (APT) and Meteor-M2-3 (LRPT)
with live SDR capture, pass prediction, and image gallery.

Backend:
- utils/weather_sat.py: SatDump process manager with image watcher
- routes/weather_sat.py: API endpoints (start/stop/images/passes/stream)
- SSE streaming for real-time capture progress
- Pass prediction using existing skyfield + TLE data
- SDR device registry integration (prevents conflicts)

Frontend:
- Sidebar panel with satellite selector and antenna build guide
  (V-dipole and QFH instructions for 137 MHz reception)
- Stats strip with status, frequency, mode, location inputs
- Split-panel layout: upcoming passes list + decoded image gallery
- Full-size image modal viewer
- SSE-driven progress updates during capture

Infrastructure:
- Dockerfile: Add SatDump build from source (headless CLI mode)
  with runtime deps (libpng, libtiff, libjemalloc, libvolk2, libnng)
- Config: WEATHER_SAT_GAIN, SAMPLE_RATE, MIN_ELEVATION, PREDICTION_HOURS
- Nav: Weather Sat entry in Space group (desktop + mobile)

https://claude.ai/code/session_01FjLTkyELaqh27U1wEXngFQ

config.py

@@ -191,6 +191,12 @@ SATELLITE_UPDATE_INTERVAL = _get_env_int('SATELLITE_UPDATE_INTERVAL', 30)
 SATELLITE_TRAJECTORY_POINTS = _get_env_int('SATELLITE_TRAJECTORY_POINTS', 30)
 SATELLITE_ORBIT_MINUTES = _get_env_int('SATELLITE_ORBIT_MINUTES', 45)
 
+# Weather satellite settings
+WEATHER_SAT_DEFAULT_GAIN = _get_env_float('WEATHER_SAT_GAIN', 40.0)
+WEATHER_SAT_SAMPLE_RATE = _get_env_int('WEATHER_SAT_SAMPLE_RATE', 1000000)
+WEATHER_SAT_MIN_ELEVATION = _get_env_float('WEATHER_SAT_MIN_ELEVATION', 15.0)
+WEATHER_SAT_PREDICTION_HOURS = _get_env_int('WEATHER_SAT_PREDICTION_HOURS', 24)
+
 # Update checking
 GITHUB_REPO = _get_env('GITHUB_REPO', 'smittix/intercept')
 UPDATE_CHECK_ENABLED = _get_env_bool('UPDATE_CHECK_ENABLED', True)