core: export says which kind of secret, so other kinds can follow

/_wallet export name <k> rather than an index straight after export. The
bare form stays the seed mnemonic, and a profile's key can be added beside
the name one without the argument having to be guessed from its shape.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Rvc3HbiWBTqbAvRT45G5oX

src/Simplex/Chat/Controller.hs

@@ -420,7 +420,7 @@ data ChatCommand
   | APIWallet
   | APIWalletCreate {recoveryPhrase :: Maybe Text}
   | APIWalletExportSeedMnemonic
-  | APIWalletExportDerivedSecret {nameIndex :: NameIndex}
+  | APIWalletExportNameSecret {nameIndex :: NameIndex}
   | APIWalletDelete
   | APISendCallInvitation ContactId CallType
   | SendCallInvitation ContactName CallType
@@ -750,7 +750,7 @@ allowRemoteCommand = \case
   APIWallet -> False
   APIWalletCreate {} -> False
   APIWalletExportSeedMnemonic -> False
-  APIWalletExportDerivedSecret {} -> False
+  APIWalletExportNameSecret {} -> False
   APIWalletDelete -> False
   _ -> True