standardize packaging, tooling, docs, CI, and licensing

mail_intake/adapters/base.pyi

@@ -1,10 +1,11 @@
 from abc import ABC, abstractmethod
-from typing import Iterator, Dict, Any
+from collections.abc import Iterator
+from typing import Any
 
 class MailIntakeAdapter(ABC):
     @abstractmethod
-    def iter_message_refs(self, query: str) -> Iterator[Dict[str, str]]: ...
+    def iter_message_refs(self, query: str) -> Iterator[dict[str, str]]: ...
     @abstractmethod
-    def fetch_message(self, message_id: str) -> Dict[str, Any]: ...
+    def fetch_message(self, message_id: str) -> dict[str, Any]: ...
     @abstractmethod
-    def fetch_thread(self, thread_id: str) -> Dict[str, Any]: ...
+    def fetch_thread(self, thread_id: str) -> dict[str, Any]: ...