feat(ci): add version-bump workflow for Renovate PRs

[lawrence-u10d]

Summary

• Adds automated version bumping for Renovate dependency update PRs
• Uses the shared reusable workflow from Unstructured-IO/infra
• Automatically bumps __version__.py, updates CHANGELOG.md, and refreshes uv.lock

How it works

When Renovate opens or updates a PR, this workflow:

1. Detects which components were changed
2. Parses conventional commit messages to determine bump type (major/minor/patch)
3. Bumps the version, updates changelog, and commits back to the PR branch

🤖 Generated with Claude Code

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Note

Medium Risk
Moderate risk because it introduces an automated workflow that can push commits (version/changelog/lockfile updates) to PR branches and depends on external reusable workflow behavior and secrets configuration.

Overview
Adds a new GitHub Actions workflow version-bump.yml that runs on pull_request events targeting main and, only for PRs opened by utic-renovate[bot], invokes the shared Unstructured-IO/infra reusable workflow to automatically apply a patch version bump and update the changelog and lockfile, committing changes back to the PR.

The workflow requests contents: write permission and wires required Renovate app credentials and a private PyPI index URL via repo vars/secrets.

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[aballman]

Looks good — standard version-bump workflow rollout.