Add shareable multi-board links with paper UI and voice notes.

Boards use /b/<uid> with no invite password; restore renamable columns,
recordings, and seeded locale notes, with first column locked.

tests/conftest.py

@@ -25,10 +25,18 @@ def client(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> TestClient:
 
 
 @pytest.fixture()
-def authed(client: TestClient) -> TestClient:
+def family_board(client: TestClient) -> dict:
+    """Bootstrap Family board id (from STORK_INVITE_TOKEN)."""
+    res = client.get("/api/resolve", params={"invite": "test-invite-token"})
+    assert res.status_code == 200
+    return res.json()
+
+
+@pytest.fixture()
+def authed(client: TestClient, family_board: dict) -> TestClient:
     res = client.post(
         "/api/session",
-        json={"invite": "test-invite-token", "display_name": "Aunt Mira"},
+        json={"board_id": family_board["id"], "display_name": "Aunt Mira"},
     )
     assert res.status_code == 200
     return client