feat(story-2.4): re-export AuthValue at top-level httpware package

Consumers writing thin wrappers around AsyncClient construction need to
type-annotate their own `auth=` parameter; without a public symbol the
only options are duplicating the union or importing from `_internal`.
Re-export `AuthValue` from `httpware._internal.auth` and add it to
`__all__`. `_normalize_auth` stays internal.

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

Author: lesnik512

src/httpware/__init__.py

@@ -1,5 +1,6 @@
 """httpware — resilience-first async HTTP client framework for Python."""
 
+from httpware._internal.auth import AuthValue
 from httpware.client import AsyncClient
 from httpware.config import ClientConfig, Limits, Timeout
 from httpware.decoders import ResponseDecoder
@@ -33,6 +34,7 @@
 __all__ = [
     "STATUS_TO_EXCEPTION",
     "AsyncClient",
+    "AuthValue",
     "BadRequestError",
     "ClientConfig",
     "ClientError",

tests/test_public_api.py

@@ -0,0 +1,15 @@
+"""Verify public API exports are correct and stable."""
+
+import httpware
+from httpware import AuthValue  # noqa: F401
+
+
+def test_all_exports_present() -> None:
+    """Verify all symbols in __all__ are actually exported."""
+    for symbol in httpware.__all__:
+        assert hasattr(httpware, symbol), f"{symbol} in __all__ but not exported"
+
+
+def test_auth_value_is_public() -> None:
+    """Verify AuthValue type alias is exported."""
+    assert "AuthValue" in httpware.__all__