Use fixed obs time for NASA fetch and atmosphere check

Previous approach: scan a 3-day window, find best moon detection,
use that timestamp.  Problems: fuzzy composite (multi-day scan could
pick a frame far from actual full moon), no clear tie between the
NASA render and a specific observable moment.

New approach — MOON_OBS_TIME_LOCAL (default 22:30 local):
  On the night of the exact phase event, look at east frames in a
  ±MOON_OBS_WINDOW_MIN (default 30 min) window around the configured
  time.  The frame closest to that time determines atmosphere opacity;
  the same time (rounded to hour) drives the NASA Dial-a-Moon fetch.
  This gives one definitive moment per phase per month.

moon_phase_monthly.py:
  - PHASE_SPEC stripped to just post_delay + enabled_key (all window/
    illumination filtering removed — obs time is the only selector)
  - run_phase() replaced with obs-time logic; opacity derived from
    detect_moon quality on that single frame
  - MOON_FULL_POST_DELAY_DAYS / MOON_QUARTER_POST_DELAY_DAYS default
    changed to 1 (post morning after the phase, frames already on disk)

moon_composite.py:
  - atmosphere blur default: output_width//10 (192px) → output_width//20
    (96px) so cloud shapes survive the blur

sky-cam.conf:
  - MOON_OBS_TIME_LOCAL=22:30, MOON_OBS_WINDOW_MIN=30
  - Post delay defaults updated to 1

test_moon_composite.py:
  - Tries real NASA SVS Dial-a-Moon API first; procedural disc only as
    fallback if API unreachable
  - Runs detect_moon on the east frame to compute real opacity
  - Single output (test_composite_out.jpg)

https://claude.ai/code/session_01HkTxpNSTWtViZzxbrbKytR

moon_composite.py

@@ -253,12 +253,13 @@ def _make_atmosphere_layer(
     it reads as "clouds between the observer and the moon" — which is
     physically correct.
 
-    blur_radius=0 → auto: output_width // 10, which smooths pixel-level
-    detail but keeps cloud-scale gradients visible.
+    blur_radius=0 → auto: output_width // 20 (96 px at 1920 wide).
+    This smooths pixel-level RTSP noise and OSD text while keeping
+    recognisable cloud shapes and sky-colour gradients intact.
     """
     src = Image.open(east_frame_path).convert('RGB')
     layer = src.resize(output_size, LANCZOS)
-    r = blur_radius if blur_radius > 0 else output_size[0] // 10
+    r = blur_radius if blur_radius > 0 else output_size[0] // 20
     return layer.filter(ImageFilter.GaussianBlur(radius=r))