style: Apply ruff auto-fixes for Python 3.12

- Update type annotations to modern syntax (dict, list, X | Y)
- Remove unnecessary elif after return
- Minor style improvements

Note: Some linting warnings remain (unused content param, inline conditions)
but these are minor style issues and do not affect functionality.
All tests pass with these changes.

src/mail/notification_compressor.py

@@ -1,13 +1,12 @@
 """Notification email compressor for terminal-friendly display."""
 
-from typing import Dict, Any, Optional
-from textual.widgets import Markdown
+from typing import Any
 
 from .notification_detector import (
-    is_notification_email,
+    NotificationType,
     classify_notification,
     extract_notification_summary,
-    NotificationType,
+    is_notification_email,
 )
 
 
@@ -22,7 +21,7 @@ class NotificationCompressor:
         """
         self.mode = mode
 
-    def should_compress(self, envelope: Dict[str, Any]) -> bool:
+    def should_compress(self, envelope: dict[str, Any]) -> bool:
         """Check if email should be compressed.
 
         Args:
@@ -37,8 +36,8 @@ class NotificationCompressor:
         return is_notification_email(envelope)
 
     def compress(
-        self, content: str, envelope: Dict[str, Any]
-    ) -> tuple[str, Optional[NotificationType]]:
+        self, content: str, envelope: dict[str, Any]
+    ) -> tuple[str, NotificationType | None]:
         """Compress notification email content.
 
         Args:
@@ -65,9 +64,9 @@ class NotificationCompressor:
 
     def _format_as_markdown(
         self,
-        summary: Dict[str, Any],
-        envelope: Dict[str, Any],
-        notif_type: Optional[NotificationType],
+        summary: dict[str, Any],
+        envelope: dict[str, Any],
+        notif_type: NotificationType | None,
     ) -> str:
         """Format summary as markdown for terminal display.
 
@@ -138,9 +137,9 @@ class DetailedCompressor(NotificationCompressor):
 
     def _format_as_markdown(
         self,
-        summary: Dict[str, Any],
-        envelope: Dict[str, Any],
-        notif_type: Optional[NotificationType],
+        summary: dict[str, Any],
+        envelope: dict[str, Any],
+        notif_type: NotificationType | None,
     ) -> str:
         """Format summary with more detail."""
 
@@ -217,5 +216,4 @@ def create_compressor(mode: str) -> NotificationCompressor:
 
     if mode == "detailed":
         return DetailedCompressor(mode=mode)
-    else:
-        return NotificationCompressor(mode=mode)
+    return NotificationCompressor(mode=mode)