feat(usage-query): decouple credentials from provider config

Add independent credential fields for usage query to support different
query endpoints and authentication methods.

Changes:
- Add `apiKey` and `baseUrl` fields to UsageScript struct
- Remove dependency on provider config credentials in query_usage
- Update test_usage_script to accept independent credential parameters
- Add credential input fields in UsageScriptModal based on template:
  * General: apiKey + baseUrl
  * NewAPI: baseUrl + accessToken + userId
  * Custom: no additional fields (full freedom)
- Auto-clear irrelevant fields when switching templates
- Add i18n text for "credentialsConfig"

Benefits:
- Query API can use different endpoint/key than provider config
- Better separation of concerns
- More flexible for various usage query scenarios

src/lib/api/usage.ts

@@ -32,6 +32,8 @@ export const usageApi = {
     appId: AppId,
     scriptCode: string,
     timeout?: number,
+    apiKey?: string,
+    baseUrl?: string,
     accessToken?: string,
     userId?: string,
   ): Promise<UsageResult> {
@@ -41,6 +43,8 @@ export const usageApi = {
         app: appId,
         scriptCode: scriptCode,
         timeout: timeout,
+        apiKey: apiKey,
+        baseUrl: baseUrl,
         accessToken: accessToken,
         userId: userId,
       });