feat(event,support): refine event page + add supporter form to Support page

Event page (Meet Student Slovenia 2026):
- Guide-style centred header with wide banner hero and caption
- Key facts on a plain background: When/Where side by side, subtle
  live-stream line, centred Register CTA, full-width note
- Partner logos (NLB patron, Embassy support) + sponsor
  Kapital Aset Menadžment DOOEL / Капитал асет менаџмент ДООЕЛ
- Inline photos between sections; em-dash removed from the subtitle
- "Support MSOS" call-out linking to the support page

Support page:
- Added the become-a-member supporter flow (supporter path only) via a
  new data-only-flow="supporter" mode in member-form.js; submits to the
  same combined Google Form tagged type=supporter
- Hero "Become a partner" button now scrolls to the form
- .ms-section carries its own brand vars so the form renders off the
  member page

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

css/pages/_member.css

@@ -145,7 +145,7 @@
 }
 
 /* ---- multi-step form ---- */
-.ms-section { max-width: 760px; margin: 0 auto; padding: 72px 24px; }
+.ms-section { max-width: 760px; margin: 0 auto; padding: 72px 24px; --mm-orange: #F2762E; --mm-teal: #2D738C; }
 .ms-head { text-align: center; margin-bottom: 28px; }
 .ms-eyebrow { display: inline-block; color: var(--mm-orange); font-weight: 700; font-size: 13px; letter-spacing: 0.06em; text-transform: uppercase; margin-bottom: 10px; }
 .ms-head h2 { font-size: 30px; margin: 0 0 8px; }