feat: auto-generate metadata markdown for each panorama

Includes: coverage, FOV, camera specs, photogrammetry reference,
equirectangular projection info, timing, image list.

Also: docker-compose user fix (1000:100) to avoid root-owned files.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -8,6 +8,7 @@ services:
       # Mount NAS astro disk (images source + output)
       - /mnt/astro/mars_rovers:/data
       - /mnt/astro/mars_rovers/images/panorama/perseverance:/output
+    user: "1000:100"  # franck:users — avoid root-owned output files
     environment:
       - MYSQL_HOST=192.168.1.42
       - MYSQL_PORT=3306