Transcribe on OpenRouter too, not just OpenAI

OpenRouter mirrors OpenAI's /audio/transcriptions field for field, so one
multipart request serves both providers and only the key, the base URL and
the model id change. That puts a dozen speech models behind the key that was
already there for the cleanup, and makes a single OpenRouter key enough for
the whole chain.

Its transcription endpoint takes no hint field, so the words from Cleanup
rules are not sent there; they still reach the cleanup model as a glossary.
Timestamps switch to openai/whisper-1, the namespaced id of the only model
that returns segment times.

The API tab is now grouped by role rather than by service, because a key no
longer belongs to a single job: both keys sit at the top, the two jobs below.
Each provider keeps its own model, so switching back and forth does not
overwrite the other one's.

dikte.py

@@ -320,7 +320,9 @@ def main():
     server.newConnection.connect(on_connection)
     app.aboutToQuit.connect(dikte.shutdown)
 
-    if command == "settings" or not dikte.conf.openai_key():
+    # No key for the chosen transcription provider means nothing can work yet,
+    # so the settings window is the only useful thing to open.
+    if command == "settings" or not dikte.conf.transcribe_target().api_key:
         dikte.open_settings()
     elif command == "toggle":
         QTimer.singleShot(0, dikte.toggle)