fix: uploadFileToFileSearchStore missing displayName

[atticoos]

Problem

Blob uploads are missing document names. As a result, when querying the FileSearchStore via the Gemini tool, GroundingMetadata doesn't include the document name, since it doesn't exist -- which means citations can't back reference the document they originated from.

Reason

uploadFileToFileSearchStore accepts a displayName per UploadToFileSearchStoreConfig

js-genai/src/types.ts

Lines 4989 to 4990 in 8683694

	/** Display name of the created document. */
	displayName?: string;

However, it is ignored, and instead the file name is determined by getFileName(file), basing the name off of the file path

js-genai/src/_api_client.ts

Lines 673 to 680 in 8683694

	private getFileName(file: string | Blob): string {
	let fileName: string = '';
	if (typeof file === 'string') {
	fileName = file.replace(/[/\\]+$/, '');
	fileName = fileName.split(/[/\\]/).pop() ?? '';
	}
	return fileName;
	}

Furthermore, when providing a Blob as the file, there is no file path, so the document is left unnamed, even if displayName is provided.

Solution

When config.displayName is provided, use that. Otherwise, fallback to existing behavior via getFileName(name)

Reproducible Steps

1. Add a file from a Blob to a FileSearchStore

client.fileSearchStores.uploadToFileSearchStore({
  fileSearchStoreName: 'fileSearchStores/X',
  file: new Blob(['I will not have a displayName'], { mimeType: 'text/plain' }),
  config: {
    displayName: 'This name will not appear',
    mimeType: 'text/plain'
  }
});

2. Query the document, it will come back without a displayName

{
  "documents": [
    {
        "name": "fileSearchStores/teststore-h96irg23frs2/documents/testfiletxt-kjvz41r4ubzb",
        "updateTime": "2025-12-18T21:09:10.504760Z",
        "createTime": "2025-12-18T21:09:09.758171Z",
        "state": "STATE_ACTIVE",
        "sizeBytes": "11",
        "mimeType": "text/plain"
    }
  ]
}

[shmishra99]

@atticoos , Thank you for raising this PR. I am escalating this PR to team for review.