chore: inline self-contained house Renovate config (#15)

Standardize Renovate to the inlined, self-contained house config (public
presets only; drops any private cross-repo extends). Preserves
repo-specific packageRules/ignoreDeps.

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## Summary by CodeRabbit

* **Chores**
* Added Renovate configuration for automated dependency management with
integrated security vulnerability handling and scheduled update
automation.

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Author: bakerboy448