Add soft-delete + recovery and tree-wide graph endpoints

Tree and person soft-delete + restore (owner-only for trees, editor for people) with recovery listings (?deleted=true); the worker already purges past the 30-day window. Adds tree-wide GET /relationships and /events so the family/pedigree view loads the whole graph in a few calls. 27 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/relationships.py

@@ -24,6 +24,15 @@ async def create_relationship(
     return RelationshipRead.model_validate(relationship)
 
 
+@router.get("/{tree_id}/relationships", response_model=list[RelationshipRead])
+async def list_relationships(
+    tree_id: uuid.UUID, session: SessionDep, current: CurrentUser
+) -> list[RelationshipRead]:
+    tree = await tree_service.get_tree(session, viewer_id=current.id, tree_id=tree_id)
+    rels = await relationship_service.list_relationships(session, viewer_id=current.id, tree=tree)
+    return [RelationshipRead.model_validate(r) for r in rels]
+
+
 @router.get(
     "/{tree_id}/persons/{person_id}/relationships",
     response_model=list[RelationshipRead],