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/config.pyi

@@ -1,9 +1,14 @@
-from typing import Optional
-
 class MailIntakeConfig:
     provider: str
     user_id: str
     readonly: bool
-    credentials_path: Optional[str]
-    token_path: Optional[str]
-    def __init__(self, provider: str = ..., user_id: str = ..., readonly: bool = ..., credentials_path: Optional[str] = ..., token_path: Optional[str] = ...) -> None: ...
+    credentials_path: str | None
+    token_path: str | None
+    def __init__(
+        self,
+        provider: str = ...,
+        user_id: str = ...,
+        readonly: bool = ...,
+        credentials_path: str | None = ...,
+        token_path: str | None = ...,
+    ) -> None: ...