chore: add dependency release age guardrails

[GangGreenTemperTatum]

Summary

• add a uv exclude-newer guardrail of 3 days
• add a Renovate minimum release age guardrail of 3 days
• enable Renovate managers for uv and pep621 project metadata

Notes

• there were no open Renovate PRs to close after this change

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Generated Summary:

• Set a minimum release age of "3 days" in the Renovate configuration to delay merges.
• Add "pep621" and "uv" to the list of dependency managers in Renovate for extended support.
• Introduce a new [tool.uv] section in pyproject.toml with an "exclude-newer" setting to align with the release age.

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