Fix mail read auto-ack and add Mayor startup directive

- Remove auto-ack on mail read so handoff messages persist
- Add STARTUP PROTOCOL directive for Mayor and Polecat roles
- Agents now get explicit instructions to check in on startup

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/mail.go

@@ -373,8 +373,9 @@ func runMailRead(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("getting message: %w", err)
 	}
 
-	// Mark as read
-	_ = mailbox.MarkRead(msgID)
+	// Note: We intentionally do NOT mark as read/ack on read.
+	// User must explicitly delete/ack the message.
+	// This preserves handoff messages for reference.
 
 	// JSON output
 	if mailReadJSON {