chore(ci): add Renovate config for grouped dependency updates

[jrusso1020]

What

Adds a .github/renovate.json config for the Renovate GitHub App, which needs to be installed on the repo after this merges.

Why

This monorepo currently has no dependency-update bot configured. Dependabot would create a separate PR per package per update (noisy for a workspace repo). Renovate supports grouping, batching, and lock-file maintenance across Bun workspaces, which scales better — it's what Vite/Vitest/Astro/Remotion all use for the same reason.

How

.github/renovate.json uses:

• config:recommended + :semanticCommits + :dependencyDashboard as the base
• Weekly schedule (before 6am on monday, LA time) so updates land in one batch, not continuously
• Grouping rules:
  • Dev-dep minor/patch updates → one PR
  • Prod-dep patch updates → one PR
  • GitHub Actions → one PR, with digest pinning
  • Major updates → gated behind the Dependency Dashboard (require approval before opening a PR)
• Workspace self-links (@hyperframes/*) disabled — those are local workspace refs, not external deps
• Lock-file maintenance on the same weekly schedule to refresh bun.lock
• PR concurrency capped at 5, hourly limit 2

One follow-up step after this merges: install the Renovate GitHub App on heygen-com/hyperframes from https://github.com/apps/renovate. Renovate will open an onboarding PR against main confirming the config.

Test plan

• JSON validates against the Renovate schema (linked in $schema)
• Manual testing performed — the config follows standard Renovate preset syntax; the actual validation happens when Renovate runs against it post-install
• Documentation updated (if applicable) — N/A