[codex] Add Dependabot cooldown periods

[hectcastro]

Summary

Adds Dependabot cooldown periods matching the dashboard configuration from 05166524bcdb0ba48a29d1de7f223693f0f4cac4.

Details

• Adds a 7 day default cooldown to all update entries.
• Adds semver-specific cooldowns for dependency ecosystems: 30 days for major updates, 7 days for minor updates, and 3 days for patch updates.
• Leaves the existing ecosystems, directories, and schedule intervals unchanged.

Validation

• Verified the resulting YAML shape against the reference dashboard change.