Replace `updated_at` with `updated_at_ms` wherever it is used as a `Validity` in cozo relations

[creatorrr]

updated_at: Validity default [floor(now()), true], should be change to =>
updated_at_ms: Validity default [floor(now() * 1000), true],

coz validity is an integer only and floor(now()) returns seconds which means that the most frequently that record can be updated is at a per second interval.