test: logs + deathSave characterization (6 tests)

- Logs.characterization.test.js: logAction (write + undo payload), clearLogs batch delete, undo (updateDoc encounter + mark undone), deathSave increment + isDying
- mock firestore getDocs: return .ref.path on docs (batch.delete support)
- mock addDoc: record full doc path not collection path

All write sites characterized. 56 frontend tests green.

src/__mocks__/firebase/firestore.js

@@ -35,7 +35,7 @@ export async function deleteDoc(docRef) {
 export async function addDoc(collRef, data) {
   const id = `auto_${MOCK_DB.nextId()}`;
   const path = `${collRef.path}/${id}`;
-  recordCall({ fn: 'addDoc', path: collRef.path, data: clone(data) });
+  recordCall({ fn: 'addDoc', path, data: clone(data) });
   MOCK_DB.set(path, clone(data));
   return { id, path };
 }
@@ -64,7 +64,7 @@ export async function getDoc(docRef) {
 export async function getDocs(collRefOrQuery) {
   const collPath = collRefOrQuery.ref ? collRefOrQuery.ref.path : collRefOrQuery.path;
   const docs = MOCK_DB.collection(collPath);
-  return { docs: docs.map(d => ({ id: d.id, data: () => d.data })) };
+  return { docs: docs.map(d => ({ id: d.id, data: () => d.data, ref: { path: `${collPath}/${d.id}` } })) };
 }
 
 // realtime — emit from mock DB, capture unsub