feat(tests): enhance modelTesterSession tests and add proxy logs tests

- Updated modelTesterSession tests to serialize assistant history as output_text and removed mime_type from input_file.
- Introduced new tests for stats proxy logs routes, covering paginated log retrieval and detailed log views with parsed billing details.
- Added server-driven tests for ProxyLogs component to validate API interactions and UI rendering based on server data.

src/server/transformers/openai/responses/conversion.test.ts

@@ -427,7 +427,6 @@ describe('convertOpenAiBodyToResponsesBody', () => {
             type: 'input_file',
             file_id: 'file_local_123',
             filename: 'report.pdf',
-            mime_type: 'application/pdf',
             file_data: 'JVBERi0xLjQK',
           },
         ],

src/server/transformers/shared/inputFile.ts

@@ -96,8 +96,6 @@ export function toResponsesInputFileBlock(file: NormalizedInputFile): Record<str
   if (file.fileId) block.file_id = file.fileId;
   if (file.fileData) block.file_data = parsedDataUrl?.data || file.fileData;
   if (file.filename) block.filename = file.filename;
-  if (file.mimeType) block.mime_type = file.mimeType;
-  else if (parsedDataUrl?.mimeType) block.mime_type = parsedDataUrl.mimeType;
   return block;
 }