fix(client): GETEX PXAT with Date must encode milliseconds

[spokodev]

Description

GETEX with the modern { type: 'PXAT', value: Date } option encodes the expiry in seconds instead of milliseconds.

In parseCommand, EXAT and PXAT shared a single switch case that ran both through transformEXAT, which does Math.floor(date.getTime() / 1000). PXAT is the millisecond absolute-timestamp variant, so a Date is sent about 1000x too small. Redis reads that number as a millisecond timestamp far in the past and deletes the key immediately instead of extending its TTL.

For a numeric value there is no visible difference (both transforms pass a number straight through), which is why the existing number-only test passed and the bug went unnoticed.

Reproduction

await client.set('session:123', 'token');
// read the value and refresh it to an absolute expiry
await client.getEx('session:123', { type: 'PXAT', value: new Date(Date.now() + 60_000) });
// key is gone: the PXAT timestamp was encoded as seconds

Fix

Route PXAT through transformPXAT (milliseconds); EXAT keeps transformEXAT (seconds). transformPXAT was already imported. Numeric values are unchanged.

Test

Added a PXAT date case to GETEX.spec.ts asserting the modern type: 'PXAT' + Date path encodes getTime() (milliseconds). It fails before the change (seconds value) and passes after (milliseconds value).

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Note

Low Risk
Small, targeted fix in GETEX argument parsing with a regression test; no auth or broad API surface changes.

Overview
Fixes GETEX when using { type: 'PXAT', value: Date }: the command encoder no longer treats PXAT like EXAT. PXAT now goes through transformPXAT (millisecond absolute timestamps); EXAT still uses transformPXAT’s second-based sibling transformEXAT.

Previously both shared one branch that always applied second encoding, so a Date on the modern PXAT path was sent ~1000× too small and Redis could expire the key immediately. Numeric PXAT values were unaffected.

Adds a GETEX.spec.ts case asserting type: 'PXAT' + Date serializes getTime() as the argument.

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[nkaradzhov]

Thanks @spokodev, this looks good!