Overlay: yellow text, lower-right position; test-sunrise uses captured frames

- fontcolor: white → yellow (both scripts)
- y position: (h-th)/2 → h-th-18 (vertically centered → lower-right corner)
- test-sunrise.sh: reverted to reading last 60 frames from capture directory
  (~10 minutes at 10s interval) instead of live RTSP capture

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

daily_sunrise_video.sh

@@ -153,9 +153,9 @@ if [ "${SUNRISE_OVERLAY_ENABLED:-true}" = "true" ]; then
     else
         DT="drawtext=textfile='${temp_text}'"
     fi
-    DT="${DT}:fontcolor=white@${SUNRISE_OVERLAY_OPACITY}"
+    DT="${DT}:fontcolor=yellow@${SUNRISE_OVERLAY_OPACITY}"
     DT="${DT}:fontsize=h/22:line_spacing=4"
-    DT="${DT}:x=w-tw-18:y=(h-th)/2"
+    DT="${DT}:x=w-tw-18:y=h-th-18"
     DT="${DT}:shadowcolor=black@0.55:shadowx=1:shadowy=1"
 fi