Add layered service/API for tenancy and people with the privacy seam

Wires the data model through repository -> service -> API/v1. The privacy engine (app/services/privacy.py) is the single enforcement point: every read resolves visibility there (tree role, tree visibility, per-person override; living-person redaction is a marked Phase 2 TODO). All writes record an attributable AuditEntry.

Endpoints: POST /users (open dev bootstrap until auth), GET /users/me, POST/GET /trees, GET /trees/{id}, and POST/GET /trees/{id}/persons. Authn is a temporary X-User-Id header shim; authz is membership-based (owner/editor/viewer). Domain errors map to 401/403/404/409. Verified on the deploy target: private tree -> 403 for non-members, missing actor -> 401, audit log populated.

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

backend/app/api/v1/persons.py

@@ -0,0 +1,43 @@
+import uuid
+
+from fastapi import APIRouter, status
+
+from app.api.deps import CurrentUser, SessionDep
+from app.schemas.person import PersonCreate, PersonRead
+from app.services import person_service, tree_service
+
+# Persons are nested under their tree (the tenant boundary).
+router = APIRouter(prefix="/trees", tags=["persons"])
+
+
+@router.post(
+    "/{tree_id}/persons",
+    response_model=PersonRead,
+    status_code=status.HTTP_201_CREATED,
+)
+async def create_person(
+    tree_id: uuid.UUID, data: PersonCreate, session: SessionDep, current: CurrentUser
+) -> PersonRead:
+    # get_tree enforces existence + view access; create_person enforces edit rights.
+    tree = await tree_service.get_tree(session, viewer_id=current.id, tree_id=tree_id)
+    person = await person_service.create_person(
+        session,
+        actor=current,
+        tree=tree,
+        given=data.given,
+        surname=data.surname,
+        gender=data.gender,
+        is_living=data.is_living,
+        privacy_setting=data.privacy,
+        notes=data.notes,
+    )
+    return PersonRead.model_validate(person)
+
+
+@router.get("/{tree_id}/persons", response_model=list[PersonRead])
+async def list_persons(
+    tree_id: uuid.UUID, session: SessionDep, current: CurrentUser
+) -> list[PersonRead]:
+    tree = await tree_service.get_tree(session, viewer_id=current.id, tree_id=tree_id)
+    persons = await person_service.list_persons(session, viewer_id=current.id, tree=tree)
+    return [PersonRead.model_validate(p) for p in persons]