[UI] Add linked sources configuration to collection settings

[jamlung-ri]

Overview

Add a "Linked Sources" section to the collection settings form where users can configure which sources have HEAD-link enabled for authoring. When a source is HEAD-linked, new concepts created while managing the collection land in that source, and HEAD content is immediately visible in the collection without a release cycle.

Acceptance Criteria

• New "Linked Sources" section in the collection edit form (src/components/repos/RepoCreate.jsx) for collection type repos
• User can search for and add a source to the linked sources list
• HEAD-link toggle per source (defaults to off)
• For MVP: source picker is filtered to sources owned by the same owner as the collection (cross-owner gated on API-side owner authorization)
• Changes saved to collection via PATCH with linked_sources payload
• Existing collections without linked sources show an appropriate empty state in the new section
• Removing a linked source is supported

Key files

(Paths are in oclweb3 — verified to exist there, not in oclweb2)

• src/components/repos/RepoCreate.jsx — collection edit form
• API: PATCH collection with linked_sources field (requires [API] Add linked_sources configuration to Collection model #2547)

Dependencies

• Requires [API] Add linked_sources configuration to Collection model #2547 (linked_sources API field)

Related

• Part of Implement linked source workflow for HEAD and version transitions #2347 (Linked Source design)