Fix double elimination with byes never finishing; hand-built brackets

Byes now cascade through the whole bracket (a slot nobody can fill is a bye or
a void), re-run on server start so stuck tournaments recover. New manual
bracket builder on the desk: pick round-1 pairings per match. Tests at 5-23
teams for both bracket types. Release 0.5.0.

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01MB7nCCAscYsb3zzkT6LHZi

server/public/admin.js

@@ -25,6 +25,17 @@
 
   document.querySelectorAll('[data-copy]').forEach(b => b.addEventListener('click', () => navigator.clipboard?.writeText(b.dataset.copy).then(() => { b.textContent = 'Copied'; })));
 
+  // manual bracket builder: highlight a team picked twice before the form is submitted
+  const pairsForm = document.querySelector('.manualform');
+  if (pairsForm) {
+    const check = () => {
+      const seen = new Map();
+      pairsForm.querySelectorAll('select[name^=a],select[name^=b]').forEach(sel => { if (sel.value) seen.set(sel.value, (seen.get(sel.value) ?? 0) + 1); });
+      pairsForm.querySelectorAll('tr').forEach(tr => tr.classList.toggle('dup', [...tr.querySelectorAll('select')].some(sel => sel.value && seen.get(sel.value) > 1)));
+    };
+    pairsForm.addEventListener('change', check); check();
+  }
+
   // keep the desk fresh when another organizer enters a score
   const ws = new WebSocket(`${location.protocol === 'https:' ? 'wss' : 'ws'}://${location.host}/ws/${slug}`);
   let last = null;