Fix overlay vertical text; test-sunrise captures fresh RTSP frames

Overlay fix (both scripts):
  Switch from text='...\n...' to drawtext's textfile= option. Writing
  each character on its own line eliminates the \n escape ambiguity in
  ffmpeg's filter-string single-quote parser, which was causing 'n' to
  appear literally instead of as a line break.

test-sunrise.sh redesign:
  Now captures NUM_FRAMES fresh RTSP frames (120s at default interval)
  at run time instead of reading pre-existing frames from the capture
  directory. The RTSP URL must be set in .env — the script fails early
  with a clear message if it is not.

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

daily_sunrise_video.sh

@@ -72,7 +72,8 @@ fi
 temp_list=$(mktemp --suffix=.txt)
 raw_video=""
 temp_audio=""
-trap 'rm -f "$temp_list" "$raw_video" "$temp_audio" 2>/dev/null || true' EXIT
+temp_text=""
+trap 'rm -f "$temp_list" "$raw_video" "$temp_audio" "$temp_text" 2>/dev/null || true' EXIT
 
 find "$image_dir" -type f -name "*.jpg" | sort | while read -r img; do
     img_sec=$(time_to_seconds "$(basename "$img" .jpg)")
@@ -143,13 +144,17 @@ echo "Speed-adjusted: ${sped_dur}s  (saved — overlay still pending)"
 SR_TIME=$(echo "$sunrise_time_local" | cut -d'-' -f1,2 | tr '-' ':')
 DT=""
 if [ "${SUNRISE_OVERLAY_ENABLED:-true}" = "true" ]; then
-    SR_VERT="${SR_TIME:0:1}\\\\n${SR_TIME:1:1}\\\\n${SR_TIME:2:1}\\\\n${SR_TIME:3:1}\\\\n${SR_TIME:4:1}"
-    DT="drawtext"
-    [ -n "$FONT" ] && DT="${DT}=fontfile='${FONT}'" || DT="${DT}"
-    DT="${DT}:text='${SR_VERT}'"
+    temp_text=$(mktemp --suffix=.txt)
+    printf '%s\n%s\n%s\n%s\n%s' \
+        "${SR_TIME:0:1}" "${SR_TIME:1:1}" "${SR_TIME:2:1}" "${SR_TIME:3:1}" "${SR_TIME:4:1}" \
+        > "$temp_text"
+    if [ -n "$FONT" ]; then
+        DT="drawtext=fontfile='${FONT}':textfile='${temp_text}'"
+    else
+        DT="drawtext=textfile='${temp_text}'"
+    fi
     DT="${DT}:fontcolor=white@${SUNRISE_OVERLAY_OPACITY}"
-    DT="${DT}:fontsize=h/22"
-    DT="${DT}:line_spacing=4"
+    DT="${DT}:fontsize=h/22:line_spacing=4"
     DT="${DT}:x=w-tw-18:y=(h-th)/2"
     DT="${DT}:shadowcolor=black@0.55:shadowx=1:shadowy=1"
 fi