Move location/music/ntfy config to .env; add paths to notifications

sky-cam.conf:
- MUSIC_DIR now uses override pattern (MUSIC_DIR="${MUSIC_DIR:-$SCRIPT_DIR/music}")
  so the real path can be set in .env without hardcoding it
- LATITUDE/LONGITUDE use override pattern; set real coords in .env to keep
  location private and out of git
- NTFY_URL now uses override pattern with empty default; set in .env
- NTFY_ENABLED moved out of comments into active config with false default

sunrise.py:
- Reads .env after sky-cam.conf so .env values override (same source order
  as sky-cam.conf itself)
- Handles ${VAR:-default} bash syntax when parsing sky-cam.conf values

All completion notifications now include the full output file path so you
can tell at a glance where the file landed:
- daily_sunrise_video.sh: "filename — Xs, sunrise at HH:MM | /full/path"
- 4-seasons.sh: "filename — Xs | /full/path"
- montage-mvt.sh: "filename | checks | /full/path | verify: ..."
- year-end-join.sh: "filename — Xmin | /full/path" (also adds [cam] to title)

install.sh .env.example now includes LATITUDE, LONGITUDE, MUSIC_DIR, NTFY_URL

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

daily_sunrise_video.sh

@@ -336,7 +336,7 @@ if $step3b_ok; then
     if ! $TEST_MODE; then
         [ -f "${cam_audio:-}" ] && rm -f "${cam_audio:-}"
         "$SCRIPT_DIR/notify.sh" "Sunrise ready: $current_date" \
-            "$(basename "$final_video") — ${actual_dur}s, sunrise at ${SR_TIME}" || true
+            "$(basename "$final_video") — ${actual_dur}s, sunrise at ${SR_TIME} | $final_video" || true
 
         # ── Rolling retention ─────────────────────────────────────────────────
         retain="${SUNRISE_RETENTION_DAYS:-10}"