Bump fallback Version to 0.13.0

[gabrielmfern]

Do not merge before #140. That PR is still open, and merging this first ships a release without it.

Releases:

• #138 — Contact.Properties is Dictionary<string, ContactPropertyValue>, the {value, type} shape the API actually returns (DEV-1624)
• #150 — deprecates the Resend.Cli tool
• #140, once merged — ContactEventData.FirstName / LastName are nullable on webhook events (DEV-1625)

Minor rather than patch, following the repo's history and because of the CLI deprecation.

🤖 Generated with Claude Code

---

Summary by cubic

Sets the fallback package version from 0.12.0 to 0.13.0 to publish the next minor release. This matters because local builds and CI without a git tag will now produce 0.13.0 artifacts that include the contact properties fix, nullable contact names in webhook payloads, and the Resend.Cli deprecation.

• Merge only after fix: allow null contact first_name and last_name on webhook events #140 so webhook FirstName/LastName nullability is included (Linear DEV-1625).
• Included changes:
  • Contact.Properties is now Dictionary<string, ContactPropertyValue> to match the API (Linear DEV-1624).
  • FirstName and LastName in contact webhook events are nullable.
  • Deprecates Resend.Cli; no immediate migration required, but plan to stop relying on it.

^{Written for commit ec74f7f. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 1 file

Confidence score: 5/5

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

<sub>Requires human review: Bumping the project version to 0.13.0 is an operational release decision that requires human coordination with other pending PRs.

Re-trigger cubic</sub>