Use content hash rather than zip hash to generate zipKey for telescopetest-io

At the moment, the hash is calculated based on zip buffer:
https://github.com/Judyzc/telescope/blob/9bbeab5a082760a59a8c196f40a033099e9b0a1e/telescopetest-io/src/pages/api/upload.ts#L75-L76

Instead, calculate the hash based on contents of all the files instead to improve reduction in storage.

Start in telescopetest-io/src/pages/api/upload.ts at lines 75–76 and trace how the upload's files and zipKey are handled. Change the hash input from the zip buffer to the contents of all files, then verify that identical contents produce the same key and improve storage reuse.

Written by the indexing model from the issue text.