Add GitHub integration recipe (community)

[tienou]

What

This PR adds a recipe for a new community integration: github — a source connector that backs up all repositories of a GitHub organization or user (or a single repository) as bare git mirrors, i.e. the full history with every branch, tag and ref, plus a JSON dump of each repository's API metadata.

Integration repository: https://github.com/tienou/integration-github (ISC, tagged v0.1.0)

Why

Plakar has connectors for databases, mailboxes, object stores, Notion… but nothing yet for git forges, while « back up our GitHub org » is a very common need (ransomware/offboarding/compliance). This fills that gap with an org-wide, incremental, agent-less approach.

Design highlights

• github://<org> or github://<org>/<repo> locations; config keys: token (falls back to $GITHUB_TOKEN), api_url (GitHub Enterprise Server support), cache_dir (persistent mirror cache → only new git objects are fetched on subsequent runs), include_forks, include_archived, metadata
• Pure Go via go-git — no git binary needed at runtime, CGO-free static build
• Built against go-kloset-sdk v1.1.0 / kloset v1.1.0 (plugin API v1.1.0), tested on plakar v1.1.4
• Since plakar spawns two importer instances per backup (scan + content passes), mirror updates are serialized with a per-repository file lock so both instances share the cache safely; go-git transient files (tmp_pack_*, *.lock) are excluded from snapshots
• Restore = plakar restore then git push --mirror
• Tested end to end: org-wide backups (12 repos), incremental re-runs, restore verified with git fsck --strict on every mirror

Notes

• checksum uses the same placeholder value as the other community recipes — happy to provide a real sha256 if you tell me what it should cover.
• If you'd rather host this in the PlakarKorp/integrations monorepo, I'm happy to send it there instead — just tell me the preferred contribution path.
• Roadmap: optional issues/PRs/releases dumps, and an exporter to push mirrors back to GitHub directly.

🤖 Generated with Claude Code

[tienou]

Bumped the recipe to v0.2.0, which adds GitHub App authentication (app_id + private key → auto-refreshed installation tokens): org-owned, read-only, non-expiring credentials instead of personal PATs — the way commercial GitHub backup products authenticate. PAT and anonymous access unchanged. Details in the README.