dave: default to OpenAI backend instead of Remote when no API key

Remote backend is only for controlling agentic sessions discovered
from relays, not a suitable default mode. Fall back to OpenAI
(with trial key) when no Anthropic key is available.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jb55

crates/notedeck_dave/src/config.rs

@@ -187,13 +187,13 @@ impl Default for ModelConfig {
                 }
             }
         } else {
-            // Auto-detect: prefer Claude if key is available, then OpenAI, then Remote
+            // Auto-detect: prefer Claude if key is available, otherwise OpenAI
+            // (with trial key fallback). Remote is only for controlling
+            // agentic sessions discovered from relays, not the default mode.
             if anthropic_api_key.is_some() {
                 BackendType::Claude
-            } else if api_key.is_some() {
-                BackendType::OpenAI
             } else {
-                BackendType::Remote
+                BackendType::OpenAI
             }
         };