018 store declared key addressing

// ASPIRATION — TODO idea pin. O2 (RULED 2026-07-04): one lvalue path
// grammar, four addressing heads — (3) declared keys: a field marked key
// at create is addressable as `pool[id: 7].hp`, and the index it needs is
// a DECLARED cost. `key:` marking spelling PROVISIONAL (candidate: an
// invocation-arg directive per ruling 8).

~import std/io
~import std/store

~std/store:create(pool, key: id) { id: i64, hp: i64 }

~std/store:insert(pool) { id: 7, hp: 50 }
| row _ |> std/store:stored { pool[id: 7].hp: pool[id: 7].hp - 10 }
    |> std/io:print.ln("hp {{ pool[id: 7].hp:d }}")