Ring buffer of the most recent console.error/window-error messages
(20 max, 500 chars each, message text only) for Task 19's report
payload. installConsoleErrorBuffer() is idempotent via a marker
stamped on the patched console.error itself (not just a module-scoped
flag), so React 18 StrictMode double-invocation or HMR re-running this
module's top level can't wrap an already-patched console.error and
build a growing chain. The patch always chains to the original.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>