docs(exec): correct execFileAsync comment — schedule.ts is not migrated

schedule.ts keeps its own schtasks wrapper because it needs the numeric exit
code (getScheduledSync checks r.code === 0), which execFileAsync deliberately
doesn't surface. The 5 migrated sites are probe/ytdlp(x2)/ffmpeg/indexer/
download.probeMeta. Comment-only.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/main/lib/exec.ts

@@ -18,9 +18,10 @@ export interface ExecResult {
 /**
  * `execFile` as a promise that never rejects (audit SIMP2/CC4/CC5). Replaces the
  * six hand-rolled `new Promise((resolve) => execFile(…, cb))` wrappers across
- * probe / ytdlp (×2) / ffmpeg / indexer / download.probeMeta / schedule — each
- * caller now maps this normalized result to its own shape instead of repeating the
- * `err.killed` timeout check and the resolve/reject plumbing.
+ * probe / ytdlp (×2) / ffmpeg / indexer / download.probeMeta — each caller now maps
+ * this normalized result to its own shape instead of repeating the `err.killed`
+ * timeout check and the resolve/reject plumbing. (schedule.ts keeps its own wrapper:
+ * it needs the numeric exit code, which this helper deliberately doesn't surface.)
  *
  * `windowsHide` defaults on (every caller wants the console window suppressed);
  * pass `timeout` / `maxBuffer` per call exactly as before.