chore(release): 0.0.3

Squash-merge lib-standardisation: adopt repo standards across packaging,
tooling, docs, and CI.

- standardize pyproject.toml (canonical packaging, lint config, extras, GSDFC pydoclint)
- add py.typed marker, modernize type hints and Google-style docstrings
- nest generated docs under docs/lib and docs/mcp; add hand-written wiki
- adopt standard Type A PyPI CI pipeline (tag==version guard + quality gate)
- promote generated CHANGELOG.md; bump version to 0.0.3

mail_intake/credentials/redis.pyi

@@ -1,4 +1,6 @@
-from typing import Optional, TypeVar, Callable, Any
+from collections.abc import Callable
+from typing import Any, TypeVar
+
 from .store import CredentialStore
 
 T = TypeVar("T")
@@ -8,8 +10,15 @@ class RedisCredentialStore(CredentialStore[T]):
     key: str
     serialize: Callable[[T], bytes]
     deserialize: Callable[[bytes], T]
-    ttl_seconds: Optional[int]
-    def __init__(self, redis_client: Any, key: str, serialize: Callable[[T], bytes], deserialize: Callable[[bytes], T], ttl_seconds: Optional[int] = ...) -> None: ...
-    def load(self) -> Optional[T]: ...
+    ttl_seconds: int | None
+    def __init__(
+        self,
+        redis_client: Any,
+        key: str,
+        serialize: Callable[[T], bytes],
+        deserialize: Callable[[bytes], T],
+        ttl_seconds: int | None = ...,
+    ) -> None: ...
+    def load(self) -> T | None: ...
     def save(self, credentials: T) -> None: ...
     def clear(self) -> None: ...