feat(config): default to WebSocket and migrate saved HTTP settings

artemis/resources/config/artemis.jsonc

@@ -2,7 +2,7 @@
 {
   "default": {
     "provider": "openai",
-    "transport": "${env:OPENAI_TRANSPORT:-http}",
+    "transport": "${env:OPENAI_TRANSPORT:-websocket}",
     "model": "${env:OPENAI_MODEL:-gpt-6-luna}",
     "timeout": "${env:OPENAI_TIMEOUT_SECONDS:-300}",
     "max_retries": "${env:OPENAI_MAX_RETRIES:-5}",