Cover edge cases: statusWriter multi-call/default/unwrap, UUID v4 format
and uniqueness, non-string panics, recovery body and log attributes,
4xx log level, default status in logging, request ID propagation,
server defaults/options/listen-error/multiple-hooks/logger, router
groups with empty prefix/inherited middleware/ordering/path params/
isolation, mount trailing slash, health content-type and POST rejection.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Introduces server/ sub-package as the server-side companion to the existing Client.
Includes Router (over http.ServeMux with groups and mounting), graceful shutdown with
signal handling, health endpoints (/healthz, /readyz), and built-in middlewares
(RequestID, Recovery, Logging). Zero external dependencies.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
