feat(models): add model test debugger for saved model configs

Let admins send real requests against configured chat, embedding, rerank,
VLM, and ASR models from settings, with thinking controls shown only when
the model supports them.

frontend/src/utils/thinkingControl.ts

@@ -69,3 +69,21 @@ export function resolveThinkingControl(
   }
   return defaultThinkingControl(provider, modelName)
 }
+
+/** Whether the debug drawer should expose Think on/off for this saved model. */
+export function modelSupportsThinking(model: {
+  type: string
+  source: string
+  name: string
+  parameters: {
+    provider?: string
+    extra_config?: { thinking_control?: string }
+  }
+}): boolean {
+  if (model.type !== 'KnowledgeQA' || model.source !== 'remote') return false
+  return resolveThinkingControl(
+    model.parameters.extra_config?.thinking_control,
+    model.parameters.provider || '',
+    model.name || '',
+  ) !== 'none'
+}