refactor(auth): simplify inline API key provider logic and improve configuration consistency

- Replaced `SyncInlineAPIKeys` with `MakeInlineAPIKeyProvider` for better clarity and reduced redundancy.
- Removed legacy logic for inline API key syncing and migration.
- Enhanced provider synchronization logic to handle empty states consistently.
- Added normalization to API key handling across configurations.
- Updated handlers to reflect streamlined provider update logic.

sdk/access/registry.go

@@ -74,10 +74,9 @@ func BuildProviders(root *config.SDKConfig) ([]Provider, error) {
 		}
 		providers = append(providers, provider)
 	}
-	if len(providers) == 0 && len(root.APIKeys) > 0 {
-		config.SyncInlineAPIKeys(root, root.APIKeys)
-		if providerCfg := root.ConfigAPIKeyProvider(); providerCfg != nil {
-			provider, err := BuildProvider(providerCfg, root)
+	if len(providers) == 0 {
+		if inline := config.MakeInlineAPIKeyProvider(root.APIKeys); inline != nil {
+			provider, err := BuildProvider(inline, root)
 			if err != nil {
 				return nil, err
 			}