[cyber-atharv]

Description

Closes #352.

In index.d.ts, ZonedDateTimeLike previously defined timeZone?: TimeZoneLike as optional.
However, when calling Temporal.ZonedDateTime.from() with a property bag, the TC39 specification (ToTemporalZonedDateTime) requires the timeZone property. At runtime, omitting timeZone throws:

TypeError: required property 'timeZone' missing or undefined

Changes

1. ZonedDateTimeLike: Made timeZone: TimeZoneLike required, reflecting runtime requirements for from(), compare(), equals(), until(), since(), and relativeTo.
2. ZonedDateTime.prototype.with: Typed parameter as Omit<ZonedDateTimeLike, 'timeZone'> so that partial date/time modifications (e.g. zdt.with({ year: 2027 })) remain valid without requiring timeZone, while correctly preventing callers from passing timeZone (which throws TypeError: with() does not support a timeZone property at runtime).

Verification

• Run Prettier check: prettier index.d.ts --check (Passed)
• Run type check on ambient definitions: tsc index.d.ts --noEmit --types --strict --lib ESNext (Passed)
• Run full project type check: tsc --noEmit (Passed)
• Validated negative test case: Calling Temporal.ZonedDateTime.from({ year: 2026, month: 1, day: 1 }) now fails TypeScript type-checking with:
  Property 'timeZone' is missing in type '{ year: number; month: number; day: number; }' but required in type 'ZonedDateTimeLike'
• Validated positive test cases: Calling Temporal.ZonedDateTime.from({ year: 2026, month: 1, day: 1, timeZone: 'UTC' }) and zdt.with({ year: 2027 }) compile cleanly.

[ptomato]

Thanks for the PR!
We're most likely going to pull in the official TypeScript types for the next release, so we're not going to continue developing these. If the types in the TypeScript repo don't handle this, then please submit the change there.