Follow-up to #99.
## Why
Evicting or deleting a local RPM removed the \`local_files\` row but left its \`rpm_metadata\` behind. Since generated repodata is built from \`rpm_metadata\`, \`primary.xml\` kept advertising a package that no longer exists, producing 404s for clients that tried to fetch it.
## Changes
- Add \`PostDeleteHook\` and \`MetadataDeleter\` provider interfaces (symmetric to the existing \`PostUploadHook\`/\`MetadataStore\`), plus a \`DeleteRPMMetadata\` DB method.
- Implement \`AfterDelete\` in the RPM provider to drop the metadata row for the deleted file.
- Route both local delete paths — the new \`evictLocal\` and the existing files handler's \`remove\` — through a shared \`deleteLocalFile\` helper that removes the file then runs the provider's post-delete hook. Non-RPM providers have no hook, so nothing changes for them.
- Cover the cleanup with a dockerised test.
Reviewed-on: #100
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
## Summary
- Upload RPMs to local repos, metadata parsed async via cavaliergopher/rpm
- Repodata (repomd.xml, primary/filelists/other.xml.gz) generated on-demand from DB — nothing stored in S3
- RPM provider implements LocalUploader, PostUploadHook, and LocalIndexer
- New rpm_metadata table for parsed RPM header data (name, version, deps, etc.)
- New provider interfaces: PostUploadHook, BlobReader, MetadataStore, RPMMetadataReader
## Test plan
- [x] Upload cowsay RPM from epel → async metadata parse confirmed in logs
- [x] repomd.xml generated with correct hashes → primary.xml.gz has correct metadata
- [x] `dnf install` from local repo: download + install successful
- [x] Bad file rejection (.txt → 400), overwrite rejection (409)
Reviewed-on: #53
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
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