Fix review feedback: Array validation, chronological pruning, safe iteration

[Copilot]

Addresses four issues from PR #26 review: missing Array.isArray guard, incorrect pruning order, unsafe iterator pattern, and missing workflow permissions.

Changes

• Array validation before parseThread: Guard against non-array API responses that would crash on .length access

  if (!Array.isArray(response.data)) {
    console.warn('Unexpected response shape from X API (thread): data is not an array');
    return null;
  }

• Chronological pruning order: Process mentions oldest-first so Set deletion removes actual oldest entries, not newest

  // X API returns newest-first, reverse to maintain chronological Set order
  for (let i = newMentions.length - 1; i >= 0; i--) {
    await this.processMention(newMentions[i]);
    this.processedMentions.add(newMentions[i].post.id);
  }

• Type-safe iterator: Replace iter.next().value as string with destructured { value, done } check to prevent exhausted iterator errors

• Workflow permissions: Add pull-requests: write to fix "Resource not accessible by integration" error when posting PR comments

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.