Multi-provider repos: private clone + identity for GitLab / Bitbucket

[serge-ivo]

Problem

The coding ENGINE is already provider-agnostic (it git-clones any URL or runs a local path, then drives Claude Code). What's GitHub-specific is only: (a) private-clone tokens via the GitHub App, (b) repo listing, (c) issues. So public GitLab/Bitbucket repos and local checkouts already work; only PRIVATE clone + listing for non-GitHub providers is missing.

Approach

• A small RepoProvider abstraction for auth: GitHub App (today) + per-provider PAT/OAuth (GitLab, Bitbucket) for private clone tokens.
• Store provider credentials with the existing envelope-encryption (same scheme as user_api_keys).
• "Add repo" accepts any provider's clone URL; private ones resolve the right token.

Scope

• lib/repo-providers.ts (token resolution by host), credentials storage, add-repo wiring.
• Issue listing/import per provider is OUT of scope here (handled by the kanban issue's adapters).

Acceptance

• Clone a private GitLab/Bitbucket repo by URL after connecting a PAT; local + public flows unchanged.

Priority

Low until a user asks — cloning already covers the common case. Tracked so it's not forgotten.

[serge-ivo]

Closing as superseded by #221. This older ticket combined GitLab/Bitbucket/private repo identity at a high level; #221 now holds the current provider-neutral Repo Coder plan with concrete provider/auth/import/build/issue layers.

[serge-ivo]

Supersession link: closed in favor of the current provider-neutral plan in #221. No implementing PR exists for this old combined ticket.