fix(subtitles): collapse layered ASS lyrics across startup and seeks

- Reconstruct fragment-only karaoke while preserving canonical animated signs
- Reprocess live subtitles after initial playback and seek updates
- Add a development launcher for playable media files

scripts/dev.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+FILE="${1:-}"
+
+if [[ ! -f "$FILE" ]]; then
+	printf 'Not a file: %s\n' "${FILE:-<missing>}" >&2
+	exit 1
+fi
+
+if ! mpv --no-config --no-terminal --msg-level=all=no --vo=null --ao=null --frames=1 -- "$FILE"; then
+	printf 'Not playable by mpv: %s\n' "$FILE" >&2
+	exit 1
+fi
+
+exec subminer app --dev --launch-mpv "$FILE"