fix: use multipart upload for Composer Registry (fixes 500 error)

server.py

@@ -97,17 +97,26 @@ def gitea_api(method, path, data=None, raw=False):
 
 def gitea_upload(url, file_data, filename):
     """Upload file to Gitea (Composer registry or release asset)."""
-    headers = {'Authorization': f'token {GITEA_TOKEN}'}
+    boundary = '----FormBoundary' + os.urandom(8).hex()
-    req = urllib.request.Request(url, data=file_data, headers=headers, method='PUT')
+    body = (
+        f'--{boundary}\r\n'
+        f'Content-Disposition: form-data; name="package"; filename="{filename}"\r\n'
+        f'Content-Type: application/zip\r\n\r\n'
+    ).encode() + file_data + f'\r\n--{boundary}--\r\n'.encode()
+    headers = {
+        'Authorization': f'token {GITEA_TOKEN}',
+        'Content-Type': f'multipart/form-data; boundary={boundary}'
+    }
+    req = urllib.request.Request(url, data=body, headers=headers, method='PUT')
     try:
         resp = urllib.request.urlopen(req, context=SSL_CTX, timeout=60)
         return {'status': 'ok', 'code': resp.getcode()}
     except urllib.error.HTTPError as e:
         code = e.code
-        body = e.read().decode()[:200]
+        msg = e.read().decode()[:200]
         if code == 409:
             return {'status': 'exists', 'code': 409, 'message': 'already exists'}
-        return {'status': 'error', 'code': code, 'message': body}
+        return {'status': 'error', 'code': code, 'message': msg}
 
 
 # --- Build logic (from Gitea, no local files) ---