Full-CRUD sweep: update endpoints for tree, source, citation, relationship, media

Closes the rule #8 gap at the API layer: PATCH endpoints + service updates for Tree (name/description/visibility), Source, Citation (page/detail/confidence), Relationship (qualifier/notes), and Media (title/attachment) — editor-gated and audited. Every core entity now has create/read/update/delete. Edit UIs for these land in the frontend batch. 37 tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Justin Paul <justin@jpaul.me>

backend/app/services/source_service.py

@@ -86,6 +86,42 @@ async def get_source(
     return source
 
 
+_SOURCE_FIELDS = {
+    "title", "author", "source_type", "repository", "url", "citation_text",
+    "publication_info", "quality_note",
+}
+
+
+async def update_source(
+    session: AsyncSession, *, actor: User, tree: Tree, source_id: uuid.UUID, changes: dict
+) -> Source:
+    if not await privacy.can_edit_tree(session, user_id=actor.id, tree=tree):
+        raise Forbidden("not an editor of this tree")
+    source = (
+        await session.execute(
+            select(Source).where(
+                Source.id == source_id, Source.tree_id == tree.id, Source.deleted_at.is_(None)
+            )
+        )
+    ).scalar_one_or_none()
+    if source is None:
+        raise NotFound("source not found")
+    for key in _SOURCE_FIELDS & changes.keys():
+        setattr(source, key, changes[key])
+    record_audit(
+        session,
+        action="update",
+        entity_type="Source",
+        entity_id=source.id,
+        tree_id=tree.id,
+        actor_user_id=actor.id,
+        after=changes,
+    )
+    await session.commit()
+    await session.refresh(source)
+    return source
+
+
 async def delete_source(
     session: AsyncSession, *, actor: User, tree: Tree, source_id: uuid.UUID
 ) -> None: