inline assistant: Fix model picker (#29136)

Release Notes:

- inline assistant: Fixed a bug where the default model would be used
even when a specific inline assistant model was configured

crates/agent/src/inline_assistant.rs

@@ -24,6 +24,7 @@ use gpui::{
     WeakEntity, Window, point,
 };
 use language::{Buffer, Point, Selection, TransactionId};
+use language_model::ConfiguredModel;
 use language_model::{LanguageModelRegistry, report_assistant_event};
 use multi_buffer::MultiBufferRow;
 use parking_lot::Mutex;
@@ -1221,9 +1222,15 @@ impl InlineAssistant {
             self.prompt_history.pop_front();
         }
 
+        let Some(ConfiguredModel { model, .. }) =
+            LanguageModelRegistry::read_global(cx).inline_assistant_model()
+        else {
+            return;
+        };
+
         assist
             .codegen
-            .update(cx, |codegen, cx| codegen.start(user_prompt, cx))
+            .update(cx, |codegen, cx| codegen.start(model, user_prompt, cx))
             .log_err();
     }