fix(admin): model selection resets after save and provider switch

Three bugs fixed:
- Removed the useEffect that synced state from config prop on every
  re-render, which caused a race condition resetting model state after
  revalidatePath triggered a server re-render.
- Reset selected model to a sensible default when switching providers,
  preventing stale model names from one provider appearing in another
  provider's model list (which made the select show the first option).
- Model select FormData names already fixed in previous commit to match
  provider-specific field names (AI_MODEL_TAGS_OLLAMA etc).

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

keep-notes/app/(main)/admin/settings/admin-settings-form.tsx

@@ -57,16 +57,6 @@ export function AdminSettingsForm({ config }: { config: Record<string, string> }
   const [isLoadingTagsModels, setIsLoadingTagsModels] = useState(false)
   const [isLoadingEmbeddingsModels, setIsLoadingEmbeddingsModels] = useState(false)
 
-  // Sync state with config
-  useEffect(() => {
-    setAllowRegister(config.ALLOW_REGISTRATION !== 'false')
-    setSmtpSecure(config.SMTP_SECURE === 'true')
-    setSmtpIgnoreCert(config.SMTP_IGNORE_CERT === 'true')
-    setTagsProvider((config.AI_PROVIDER_TAGS as AIProvider) || 'ollama')
-    setEmbeddingsProvider((config.AI_PROVIDER_EMBEDDING as AIProvider) || 'ollama')
-    setSelectedTagsModel(config.AI_MODEL_TAGS || '')
-    setSelectedEmbeddingModel(config.AI_MODEL_EMBEDDING || '')
-  }, [config])
 
   // Fetch Ollama models
   const fetchOllamaModels = useCallback(async (type: 'tags' | 'embeddings', url: string) => {
@@ -287,7 +277,16 @@ export function AdminSettingsForm({ config }: { config: Record<string, string> }
                   id="AI_PROVIDER_TAGS"
                   name="AI_PROVIDER_TAGS"
                   value={tagsProvider}
-                  onChange={(e) => setTagsProvider(e.target.value as AIProvider)}
+                  onChange={(e) => {
+                    const newProvider = e.target.value as AIProvider
+                    setTagsProvider(newProvider)
+                    const defaultModels: Record<string, string> = {
+                      ollama: '',
+                      openai: MODELS_2026.openai.tags[0],
+                      custom: MODELS_2026.custom.tags[0],
+                    }
+                    setSelectedTagsModel(defaultModels[newProvider] || '')
+                  }}
                   className="flex h-10 w-full rounded-md border border-input bg-background px-3 py-2 text-sm ring-offset-background focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2"
                 >
                   <option value="ollama">{t('admin.ai.providerOllamaOption')}</option>
@@ -417,7 +416,16 @@ export function AdminSettingsForm({ config }: { config: Record<string, string> }
                   id="AI_PROVIDER_EMBEDDING"
                   name="AI_PROVIDER_EMBEDDING"
                   value={embeddingsProvider}
-                  onChange={(e) => setEmbeddingsProvider(e.target.value as AIProvider)}
+                  onChange={(e) => {
+                    const newProvider = e.target.value as AIProvider
+                    setEmbeddingsProvider(newProvider)
+                    const defaultModels: Record<string, string> = {
+                      ollama: '',
+                      openai: MODELS_2026.openai.embeddings[0],
+                      custom: MODELS_2026.custom.embeddings[0],
+                    }
+                    setSelectedEmbeddingModel(defaultModels[newProvider] || '')
+                  }}
                   className="flex h-10 w-full rounded-md border border-input bg-background px-3 py-2 text-sm ring-offset-background focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2"
                 >
                   <option value="ollama">{t('admin.ai.providerOllamaOption')}</option>