Improve closed branch experience

• expose closing-related properties for editing in TK
• sibyl: fetch branches on startup, and use it to remove aggregations for branches where hideHoldings is true
• proxy: fetch branches on startup, and use it to ignore holdings for branches where hideHoldings is true
• rename properties to match actual use: closed => hideHoldings, active => isPickupBranch

euler2 sql migrations:

CREATE TABLE tmp_library (
    id          TEXT PRIMARY KEY,
    name        TEXT NOT NULL GENERATED ALWAYS AS (json_extract(data, '$.name')) STORED,
    data        JSON NOT NULL DEFAULT '{}',
    created_by  TEXT NOT NULL REFERENCES editor (id),
    updated_by  TEXT NOT NULL REFERENCES editor (id),
    created_at  DATETIME NOT NULL,
    updated_at  DATETIME NOT NULL,
    archived_at DATETIME
);

INSERT INTO tmp_library (id, data, created_by, updated_by, created_at, updated_at, archived_at)
SELECT id, data, created_by, updated_by, created_at, updated_at, archived_at FROM library;

DROP TABLE library;

ALTER TABLE tmp_library RENAME TO library;

UPDATE library SET data=json_set(data,
    '$.hideHoldings', json_extract(data, '$.closed'),
    '$.isPickupBranch', json_extract(data, '$.active'));

UPDATE library SET data=json_remove(data,
    '$.closed',
    '$.active');