Update skills for deletion protection and deploy inspection

[cursor]

Summary

• Reflect https://planetscale.com/changelog/cli-deploy-request-inspect by documenting read-only deploy-request queue/operations/deployment inspection and classifying per-request throttler updates as approval-gated mutations.
• Reflect https://planetscale.com/changelog/database-and-branch-deletion-protection by adding database and branch deletion-protection inventory, safety-review, approval-gate, autonomous-loop, CLI, and Terraform guidance.

Why

These changelog entries add new operational surfaces that affect how agents should inspect active Vitess deploy requests, tune throttling, and avoid accidental database or branch deletion across Vitess and Postgres.

Validation

• git diff --check HEAD~1 HEAD