Fix bugs found in post-refactor audit

- verify-mvt.sh: remove dead first _info= line (used MVT_START before
  defined); fix JPEG size loop to accumulate bytes correctly and display
  human-readable total; show size in delete confirmation
- montage-mvt.sh: grep -c uses || echo 0 instead of || true to be
  unambiguous about the no-match value under set -e
- capture.sh, capture-watchdog.sh: require camera name arg, remove
  silent SUNRISE_CAM fallback
- migrate-seasons.sh: require --cam arg, error if missing
- README.md, sky-cam.conf: remove stale fullday-video.sh references;
  README pipeline diagram updated to show verify-mvt.sh

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

migrate-seasons.sh

@@ -41,7 +41,11 @@ while [[ $# -gt 0 ]]; do
     shift
 done
 
-[ -z "$CAM" ] && CAM="$SUNRISE_CAM"
+if [ -z "$CAM" ]; then
+    echo "Usage: $0 --cam <camera-name> [--dry-run] [OLD_ROOT]"
+    echo "  e.g. $0 --cam east ~/drives/local-2tb/movies/sunrise"
+    exit 1
+fi
 NEW_ROOT="$MOVIES_DIR/$CAM/2025"
 
 echo "Old archive : $OLD_ROOT"