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/models/thread.pyi

@@ -1,12 +1,19 @@
 from datetime import datetime
-from typing import List, Set, Optional
+
 from .message import MailIntakeMessage
 
 class MailIntakeThread:
     thread_id: str
     normalized_subject: str
-    participants: Set[str]
-    messages: List[MailIntakeMessage]
-    last_activity_at: Optional[datetime]
-    def __init__(self, thread_id: str, normalized_subject: str, participants: Set[str] = ..., messages: List[MailIntakeMessage] = ..., last_activity_at: Optional[datetime] = ...) -> None: ...
+    participants: set[str]
+    messages: list[MailIntakeMessage]
+    last_activity_at: datetime | None
+    def __init__(
+        self,
+        thread_id: str,
+        normalized_subject: str,
+        participants: set[str] = ...,
+        messages: list[MailIntakeMessage] = ...,
+        last_activity_at: datetime | None = ...,
+    ) -> None: ...
     def add_message(self, message: MailIntakeMessage) -> None: ...