Patch Every.org widget to forward partner_donation_id to donation URL

The widget v0.4 defines PARTNER_DONATION_ID in its URL params enum but
never reads or forwards it. This adds 5 surgical patches (mirroring the
existing partnerMetadata pipeline) so partner_donation_id flows from
button href → widget config → Every.org donation URL. Also prettifies
the widget JS for maintainability and adds OSE patch comments.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: vinogradovkonst

public/js/everyorg-endowment-button.js

@@ -349,8 +349,9 @@ import { OpenPanelComponent } from '@openpanel/astro';
         };
         const metadataB64 = btoa(JSON.stringify(metadata));
         const [base, hash] = href.split('#');
+        // Inject partner_donation_id (visitor UUID) so the widget forwards it to Every.org
         link.setAttribute('href',
-            base + '&partner_metadata=' + encodeURIComponent(metadataB64)
+            base + '&partner_donation_id=' + encodeURIComponent(window.__oseVisitorId) + '&partner_metadata=' + encodeURIComponent(metadataB64)
             + (hash ? '#' + hash : ''));
     });