composite: use east frame background with bilateral filter at 70% zoom

Switch monthly pipeline from render_phase_closeup (black background) to
composite_full_moon (east frame + NASA moon overlay) when an east frame
and detection are available.  Falls back to render_phase_closeup when
east verification is disabled.

Changes:
- composite_full_moon: bilateral filter (d=9, σ=75) on upscaled background
  to smooth pixelation artifacts before compositing the NASA moon
- composite_full_moon: caption now placed below the moon disk instead of
  overlapping it (paste_y + target_size + 12)
- run_phase: keep detection result (best_det) alongside best_frame
- _render_and_post: accept east_frame + detection, route to the right renderer
- Monthly pipeline uses moon_height_pct=0.70 for the east-frame composite

https://claude.ai/code/session_01JieSeNQZ3X6fhsb11YyJrK

moon_composite.py

@@ -191,6 +191,11 @@ def composite_full_moon(
     crop = src.crop((left, top, left + crop_w, top + crop_h))
     bg = crop.resize(output_size, LANCZOS)
 
+    # ── Smooth upscaling artifacts in the sky background ──
+    import cv2
+    bg_arr = cv2.bilateralFilter(np.array(bg), d=9, sigmaColor=75, sigmaSpace=75)
+    bg = Image.fromarray(bg_arr)
+
     # ── Where is the moon's center within the upscaled background? ──
     moon_x_in_crop = cx - left
     moon_y_in_crop = cy - top
@@ -230,10 +235,11 @@ def composite_full_moon(
     paste_y = max(0, min(paste_y, output_size[1] - target_size))
     bg.paste(ref_rot, (paste_x, paste_y), mask)
 
-    # ── Caption ──
+    # ── Caption — below the moon disk, not overlapping it ──
     if caption:
         draw = ImageDraw.Draw(bg)
-        _draw_caption(draw, caption, (22, output_size[1] - 48), output_size[0])
+        caption_y = min(paste_y + target_size + 12, output_size[1] - 30)
+        _draw_caption(draw, caption, (22, caption_y), output_size[0])
 
     Path(out_path).parent.mkdir(parents=True, exist_ok=True)
     bg.save(out_path, quality=92)