Register ChatKit event listeners before applying options

[sylvesterkaczmarek]

Problem

The React wrapper calls setOptions in a layout effect, but registers event listeners in a later passive effect. Synchronous events from initial configuration are missed. On reconfiguration, they can reach the previous handlers instead of the current ones.

Change

Register listeners in a layout effect before applying options. Retain AbortController cleanup and the existing late-definition cancellation path. Add a patch changeset and development-only DOM test dependencies.

Validation

• 22 tests passed, including six React/DOM lifecycle cases. Three new cases fail on unchanged production code.
• Coverage includes initial ready/error events, current handlers during reconfiguration, Strict Mode replay, late custom-element definition, unmount before definition, and listener cleanup.
• CI=1 pnpm check passed formatting, lint, type checks, documentation build, and tests in an isolated temporary checkout. Changed files were byte-checked against the publication checkout.
• React bindings build passed for ESM, CommonJS, and declaration output. git diff --check passes.

Node 26.8.1, React 19.1.1, Happy DOM 20.14.5 on macOS arm64. Tests use the production wrapper and a synthetic custom element that emits events from setOptions. The hosted ChatKit component and live API were not exercised. Runtime dependencies and public interfaces are unchanged.

Reproduced against 22613848a656077a408788f028c7727e38d10449.