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/api/v1/trees.py

@@ -3,7 +3,7 @@ import uuid
 from fastapi import APIRouter, status
 
 from app.api.deps import CurrentUser, SessionDep
-from app.schemas.tree import TreeCreate, TreeRead
+from app.schemas.tree import TreeCreate, TreeRead, TreeUpdate
 from app.services import tree_service
 
 router = APIRouter(prefix="/trees", tags=["trees"])
@@ -38,6 +38,16 @@ async def get_tree(tree_id: uuid.UUID, session: SessionDep, current: CurrentUser
     return TreeRead.model_validate(tree)
 
 
+@router.patch("/{tree_id}", response_model=TreeRead)
+async def update_tree(
+    tree_id: uuid.UUID, data: TreeUpdate, session: SessionDep, current: CurrentUser
+) -> TreeRead:
+    tree = await tree_service.update_tree(
+        session, actor=current, tree_id=tree_id, changes=data.model_dump(exclude_unset=True)
+    )
+    return TreeRead.model_validate(tree)
+
+
 @router.delete("/{tree_id}", status_code=status.HTTP_204_NO_CONTENT)
 async def delete_tree(tree_id: uuid.UUID, session: SessionDep, current: CurrentUser) -> None:
     await tree_service.delete_tree(session, actor=current, tree_id=tree_id)