Type the defaultHeaders as Record<string, string> to fix TS2322 error
when spreading headers into fetch options.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
The hardcoded 'Content-Type: application/json' header was conflicting
with multipart/form-data uploads. When body is FormData, we now omit
the Content-Type header to let the browser set the correct
'multipart/form-data; boundary=...' header.
Fixes 415 Unsupported Media Type error on photo uploads.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
