Fix list-accounts on fresh install and display-name on existing token

Add InitSchema call in list-accounts so a fresh install gets "No
accounts found" instead of "no such table: sources".

Apply --display-name on the early-return path in add-account when a
token already exists, so the flag isn't silently ignored.

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

Author: wesm

cmd/msgvault/cmd/addaccount.go

@@ -62,10 +62,15 @@ Examples:
 		if oauthMgr.HasToken(email) {
 			// Still create the source record - needed for headless setup
 			// where token was copied but account not yet registered
-			_, err = s.GetOrCreateSource("gmail", email)
+			source, err := s.GetOrCreateSource("gmail", email)
 			if err != nil {
 				return fmt.Errorf("create source: %w", err)
 			}
+			if accountDisplayName != "" {
+				if err := s.UpdateSourceDisplayName(source.ID, accountDisplayName); err != nil {
+					return fmt.Errorf("set display name: %w", err)
+				}
+			}
 			fmt.Printf("Account %s is ready.\n", email)
 			fmt.Println("You can now run: msgvault sync-full", email)
 			return nil

cmd/msgvault/cmd/list_accounts.go

@@ -31,6 +31,10 @@ Examples:
 		}
 		defer s.Close()
 
+		if err := s.InitSchema(); err != nil {
+			return fmt.Errorf("init schema: %w", err)
+		}
+
 		sources, err := s.ListSources("")
 		if err != nil {
 			return fmt.Errorf("list accounts: %w", err)