docs(middleware): LoggingMiddleware uses logging, not print()

The example previously used `print(...)` to demonstrate a middleware that
records inbound/outbound traffic. CLAUDE.md lists "No print()" as a
non-negotiable architecture invariant, so the doc example would fail CI
in a user's own project if they followed the project's conventions.

Rewrite with a module-level `_LOGGER = logging.getLogger("myapp.logging_middleware")`
and `_LOGGER.info(...)` calls, matching the existing RequestIdMiddleware
example's style further down the same file.

Closes audit Nit finding (docs/middleware.md:156-161) from
planning/audit/2026-06-07-deep-audit.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: lesnik512

docs/middleware.md

@@ -147,17 +147,22 @@ from httpware import Middleware, Next, before_request, after_response, on_error
 A sync `Middleware` is a structural protocol — any callable with the right signature satisfies it:
 
 ```python
+import logging
+
 import httpx2
 
 from httpware import Client
 from httpware.middleware import Next
 
 
+_LOGGER = logging.getLogger("myapp.logging_middleware")
+
+
 class LoggingMiddleware:
     def __call__(self, request: httpx2.Request, next: Next) -> httpx2.Response:  # noqa: A002
-        print(f"-> {request.method} {request.url}")
+        _LOGGER.info("-> %s %s", request.method, request.url)
         response = next(request)
-        print(f"<- {response.status_code}")
+        _LOGGER.info("<- %s", response.status_code)
         return response