Fix UnicodeEncodeError in caption drawing

The default PIL bitmap font only covers latin-1, so the em dash (U+2014)
in captions raised UnicodeEncodeError at runtime.

Add _load_font() which tries DejaVu Sans TTF from common system paths
(the fonts-dejavu package is already a listed dependency) and falls back
to the PIL default only when no TTF is found.  Add _draw_caption() which
wraps both the font load and the two-pass drop-shadow draw, and sanitises
the string for the bitmap fallback path so it never crashes.

Replace both raw draw.text caption blocks in composite_full_moon() and
render_phase_closeup() with _draw_caption().

https://claude.ai/code/session_01HkTxpNSTWtViZzxbrbKytR

moon_composite.py

@@ -36,7 +36,7 @@ from datetime import datetime, timezone
 from pathlib import Path
 
 import numpy as np
-from PIL import Image, ImageDraw, ImageFilter
+from PIL import Image, ImageDraw, ImageFilter, ImageFont
 
 # Pillow ≥ 10 renamed resampling constants
 try:
@@ -46,6 +46,39 @@ except AttributeError:  # Pillow < 10
     LANCZOS = Image.LANCZOS
     BICUBIC = Image.BICUBIC
 
+# Common DejaVu Sans paths across distros; first hit wins.
+_DEJAVU_CANDIDATES = [
+    '/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf',
+    '/usr/share/fonts/dejavu/DejaVuSans.ttf',
+    '/usr/share/fonts/TTF/DejaVuSans.ttf',
+    '/Library/Fonts/DejaVuSans.ttf',  # macOS homebrew
+]
+
+
+def _load_font(size: int = 18) -> ImageFont.ImageFont:
+    """Return a Unicode-capable font at `size` pt, or the PIL default."""
+    for path in _DEJAVU_CANDIDATES:
+        try:
+            return ImageFont.truetype(path, size)
+        except (OSError, IOError):
+            pass
+    return ImageFont.load_default()
+
+
+def _draw_caption(draw: ImageDraw.ImageDraw, caption: str,
+                  xy: tuple[int, int], output_w: int) -> None:
+    """Draw a drop-shadow caption, sanitising characters the default font
+    cannot encode when no TTF is available."""
+    font = _load_font(max(14, output_w // 100))
+    # If we fell back to the bitmap default font it only handles latin-1; strip
+    # anything outside that range rather than crashing.
+    if not hasattr(font, 'path'):
+        caption = caption.encode('latin-1', errors='replace').decode('latin-1')
+        caption = caption.replace('\x3f', '-')  # '?' placeholder → dash
+    x, y = xy
+    draw.text((x + 2, y + 2), caption, fill=(0, 0, 0), font=font)
+    draw.text((x,     y),     caption, fill=(220, 220, 220), font=font)
+
 
 def _square_crop_to_disk(ref: Image.Image, threshold: int = 25) -> Image.Image:
     """Tight-crop a reference moon image to the disk's bounding square.
@@ -200,9 +233,7 @@ def composite_full_moon(
     # ── Caption ──
     if caption:
         draw = ImageDraw.Draw(bg)
-        # Drop shadow for legibility
+        _draw_caption(draw, caption, (22, output_size[1] - 48), output_size[0])
-        draw.text((24, output_size[1] - 44), caption, fill=(0, 0, 0))
-        draw.text((22, output_size[1] - 46), caption, fill=(220, 220, 220))
 
     Path(out_path).parent.mkdir(parents=True, exist_ok=True)
     bg.save(out_path, quality=92)