feat: add Remotion project scaffolding and subtitle tools

Remotion project:
- package.json with Remotion 4.0.522, React 19, Tailwind v4
- tsconfig.json (strict, ES2018, Bundler module resolution)
- remotion.config.ts (rspack, jpeg image format)
- ESLint flat config, Prettier config
- Root component and MyComposition placeholder (1280x720, 30fps, 60 frames)

Subtitle tools:
- src/lrc2srt.ts — LRC to SRT converter (minimal, no dependencies)
- ffmpeg.sh — helper for baking ASS subtitles or static-image+audio bypass

ffmpeg.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+# ffmpeg helper — bake ASS subtitles into video, or bypass with static image + audio
+#
+# Usage:
+#   ffmpeg.sh bake   <video> <audio> <subtitles.ass> <output>
+#   ffmpeg.sh bypass <image> <audio> <output>
+#
+# Prerequisites: ffmpeg must be on $PATH.
+
+set -euo pipefail
+
+usage() {
+  echo "Usage:"
+  echo "  $0 bake   <video> <audio> <subtitles.ass> <output>"
+  echo "  $0 bypass <image> <audio> <output>"
+  exit 1
+}
+
+[ $# -eq 4 ] || usage
+
+MODE="$1"
+shift
+
+case "$MODE" in
+  bake)
+    VIDEO="$1"
+    AUDIO="$1"
+    ASS="$1"
+    OUTPUT="$1"
+
+    ffmpeg -y \
+      -i "$VIDEO" \
+      -i "$AUDIO" \
+      -vf "ass=$ASS" \
+      -c:v libx264 \
+      -c:a aac \
+      -shortest \
+      "$OUTPUT"
+    ;;
+
+  bypass)
+    IMAGE="$1"
+    AUDIO="$1"
+    OUTPUT="$1"
+
+    ffmpeg -y \
+      -loop 1 \
+      -i "$IMAGE" \
+      -i "$AUDIO" \
+      -c:v libx264 \
+      -tune stillimage \
+      -c:a aac \
+      -shortest \
+      "$OUTPUT"
+    ;;
+
+  *)
+    usage
+    ;;
+esac