feat: 5 dramatic extra themes (neon/terminal/blueprint/sunset) + board/review/layout polish

- Themes: add neon (cyber gradient), terminal (green CRT), blueprint (graph
  paper) and sunset (vaporwave) alongside the default Light (Y2K paper) and
  Dark. Theme toggle now cycles all; profile selector lists them; server
  validates against a shared whitelist.
- Bounty cards now show the project (customer) name.
- Remove the celebratory emoji from the empty Review Queue.
- Full-width h1 underline rule; My Tasks columns stack vertically for more
  room per task; card action buttons wrap/right-align so they never overflow.

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

web/static/js/nav.js

@@ -16,9 +16,12 @@ const themeBtn = document.getElementById('nav-theme');
 if (themeBtn) {
   themeBtn.addEventListener('click', async () => {
     const el = document.documentElement;
-    const next = el.dataset.theme === 'dark' ? 'light' : 'dark';
+    const themes = (el.dataset.themes || 'light,dark').split(',');
+    const cur = themes.indexOf(el.dataset.theme);
+    const next = themes[(cur + 1) % themes.length];
     el.dataset.theme = next;
     try { localStorage.setItem('theme', next); } catch (e) { /* ignore */ }
+    toast('Theme: ' + next);
     if (document.body.dataset.loggedIn === '1') {
       try {
         await api('PATCH', '/api/v1/profile', { settings: { theme: next } });