Member dashboard: drill-down tree, list view, legend, and strategy-aware referral tool

- "Your team" now covers the member's FULL leg with click-to-drill
  pyramid, breadcrumb, and a list-view toggle (mirrors the admin matrix).
- Legend under both the member tree and admin matrix explaining the
  qualified checkmark, tier badges, and downline rollup.
- "Share this position" card: while under 2/2 it's a personal recruiting
  tool — per-member QR (vendored qrcode-generator, CSP-safe), copy link,
  and a join CTA carrying the member's ID as sponsor. At 2/2 the page
  automatically retires the link and redirects sharing to the team
  rotator, so personal referrals can't undermine the moving-link
  strategy.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

public/admin.js

@@ -117,7 +117,7 @@ function renderList(){
 }
 function renderMatrix(){
   const d=matrixUI.data;
-  const head=`${d.memberCount} positions · snapshot ${new Date(d.snapshotAt).toISOString().replace('T',' ').slice(0,16)} UTC · P = Premium, S = Standard`;
+  const head=`${d.memberCount} positions · snapshot ${new Date(d.snapshotAt).toISOString().replace('T',' ').slice(0,16)} UTC · <span class="mtp-qmark" style="position:static;display:inline-grid;vertical-align:middle">✓</span> qualified (2/2 directs) · <span class="mt-badge mt-prem">P</span> Premium · <span class="mt-badge">S</span> Standard · ⬇ full downline below that position`;
   document.getElementById('treeToggleBtn').classList.remove('hidden');
   document.getElementById('treeToggleBtn').textContent=matrixUI.mode==='pyramid'?'List view':'Pyramid view';
   if(matrixUI.mode==='pyramid')renderPyramid();else renderList();