fix: daily_sunrise_video.sh exits non-zero, blocking OnSuccess= upload

Conditional expressions like `[ "$count" -gt 0 ] && echo ...` return 1
when count is 0 (nothing to delete). Under set -euo pipefail with no
explicit exit 0, that false becomes the script's exit code. systemd sees
failure, OnSuccess= for sunrise2mm.py never fires, and the Mattermost
upload is silently skipped every day.

Fix: add || true to all end-of-script conditional-echo statements and to
the cam_audio cleanup line, then add an explicit exit 0 so the success
path always exits cleanly.

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

daily_sunrise_video.sh

@@ -356,10 +356,10 @@ if $step3b_ok; then
                 -name "*-daily-sunrise-test.mp4" \
                 -mtime +"$demo_retain" -print -delete 2>/dev/null | wc -l)
             [ "$deleted_demo" -gt 0 ] && \
-                echo "Demo retention: deleted $deleted_demo test file(s) older than ${demo_retain} days"
+                echo "Demo retention: deleted $deleted_demo test file(s) older than ${demo_retain} days" || true
         fi
     else
-        [ -f "${cam_audio:-}" ] && rm -f "${cam_audio:-}"
+        [ -f "${cam_audio:-}" ] && rm -f "${cam_audio:-}" || true
         "$SCRIPT_DIR/notify.sh" "Sunrise ready: $current_date" \
             "$(basename "$final_video") — ${actual_dur}s, sunrise at ${SR_TIME} | $final_video" || true
 
@@ -370,7 +370,9 @@ if $step3b_ok; then
                 -path "*/sunrise-only/*-daily-sunrise.mp4" \
                 -mtime +"$retain" -print -delete 2>/dev/null | wc -l)
             [ "$deleted_old" -gt 0 ] && \
-                echo "Retention: deleted $deleted_old sunrise video(s) older than ${retain} days"
+                echo "Retention: deleted $deleted_old sunrise video(s) older than ${retain} days" || true
         fi
     fi
 fi
+
+exit 0