feat: add Broadcasts.recipients method

[dielduarte]

Adds Resend::Broadcasts.recipients(id, params) for GET /broadcasts/{id}/recipients.

Spec: resend/resend-openapi#97
Node reference: resend/resend-node#1078

Tests: 357 passed. rubocop clean.

---

Summary by cubic

Adds Resend::Broadcasts.recipients(id, params) to list broadcast recipients via GET /broadcasts/{id}/recipients. Previously the SDK could not fetch recipients; now clients can filter by event type and paginate, and 404s raise Resend::Error::NotFoundError. Removes the recipients example that required an arbitrary sleep.

• Require params[:type] (sent, delivered, opened, clicked, bounced, complained, unsubscribed, suppressed); raise ArgumentError if missing.
• Support filters: email; bounce_type when type is 'bounced' (permanent, transient, undetermined); limit, after, before via Resend::PaginationHelper.
• Return extra fields by type: opened includes count; clicked includes count and clicked_links; bounced includes bounce_type.
• Tests verify request paths, per-type fields, and that 404 raises NotFoundError.

^{Written for commit b6c8b67. Summary will update on new commits.}

[cubic-dev-ai]

All reported issues were addressed across 3 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

0 issues found across 2 files (changes from recent commits).

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

<sub>Requires human review: Auto-approval blocked by 2 unresolved issues from previous reviews.

Re-trigger cubic</sub>

[klotty]

0 issues found across 1 file (changes from recent commits).

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

<sub>Auto-approved: Adds the recipients method to the Broadcasts module, allowing users to fetch recipients for a specific broadcast with support for event type filtering and pagination. The implementation follows standard SDK patterns.

Re-trigger cubic</sub>