feat: add broadcasts.ClickedLinks() method

[dielduarte]

Adds GET /broadcasts/{id}/clicked-links — paginated list of a broadcast's clicked links (url, clicks, unique_clicks).

Spec: resend/resend-openapi#95
Reference implementation: resend/resend-node#1077

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Summary by cubic

Adds GET /broadcasts/{id}/clicked-links to fetch a broadcast’s clicked links with pagination. Previously the client could not fetch clicked links; now it supports per-link analytics and validates empty broadcastId.

• Defines ListBroadcastClickedLinksResponse and BroadcastClickedLink with id (opaque pagination cursor), url, clicks, and unique_clicks.
• Adds BroadcastsSvc methods: ClickedLinks, ClickedLinksWithContext, and ClickedLinksWithOptions; pagination via ListOptions (limit, after); returns "[ERROR]: broadcastId cannot be empty" if missing.
• Tests cover default retrieval, pagination query params, and validation.
• Migration: if you implement BroadcastsSvc, add the three new methods.

^{Written for commit 98756e2. Summary will update on new commits.}

[cubic-dev-ai]

All reported issues were addressed across 2 files

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[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 support for retrieving broadcast clicked links via the new ClickedLinks method, including pagination and unit tests.

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