fix(core): gate parseBeats on schema version

parseBeats accepted any object with a beats array, so a future v2 beat file
(with changed semantics) would be parsed silently as v1. Reject anything whose
version is not 1, treating an unknown version like an absent/invalid file.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>

Author: vanceingalls

packages/core/src/beats/beatFile.ts

@@ -59,7 +59,9 @@ export function serializeBeats(times: number[], strengths: number[], audio: stri
 export function parseBeats(content: string): { times: number[]; strengths: number[] } | null {
   try {
     const data = JSON.parse(content) as BeatFileData;
-    if (!data || !Array.isArray(data.beats)) return null;
+    // Gate on the schema version so a future v2 file (with changed semantics)
+    // isn't silently parsed as v1 — an unknown version is treated as absent.
+    if (!data || data.version !== 1 || !Array.isArray(data.beats)) return null;
     const times: number[] = [];
     const strengths: number[] = [];
     for (const b of data.beats) {