Addresses review feedback on #347 regarding performance issues when globs expand to large file lists.

Changes

• Sequential stat with early exit: Replaced Promise.all(paths.map(stat)) with sequential iteration that terminates immediately when MAX_SUBJECT_COUNT is reached
• Fixed off-by-one: Moved limit check before array push to correctly enforce 1024 maximum (was allowing 1025)

Before:

const stats = await Promise.all(paths.map(async p => fs.stat(p)))
const files = paths.filter((_, i) => stats[i].isFile())

if (files.length > MAX_SUBJECT_COUNT) {
  throw new Error(...)
}

After:

const files: string[] = []
for (const p of paths) {
  const stat = await fs.stat(p)
  if (stat.isFile()) {
    if (files.length >= MAX_SUBJECT_COUNT) {
      throw new Error(...)
    }
    files.push(p)
  }
}

Prevents issuing thousands of concurrent stat calls that could hit OS file descriptor limits or cause significant slowdown.

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