fix(encryption): an encrypted object shaped like the Date marker is revived as a Date whatever its value #52

EncryptionModifier stores a Date inside an encrypted value as { "type": "Date", "value": "<toUTCString>" } and date_decoder (src/modifiers/encryption.ts) turns every object with exactly the keys type and value, type === "Date", back into new Date(value.value) without checking what value.value is. A caller who stores such an object themselves gets a different value back.

Reproduction (built package, 0.1.11):

const lib = require("./dist/index.js");
class T extends lib.Table.with(lib.EncryptionModifier) {}
lib.Encrypted({ secretKey: "0123456789abcdef0123456789abcdef" })(T.prototype, "card");
const row = new T();
row.card = { type: "Date", value: 123 };
console.log(row.card instanceof Date, row.card); // true, 1970-01-01T00:00:00.123Z: the stored object is not returned

Expected: only the marker date_encoder writes (value a string toUTCString can have produced) is revived, and any other object comes back as stored. Fixing it is a behaviour change, so the 0.2.17 burn-down left it (six rows of encryption.ts:37-43 stay under the ratchet).