feat: presence beyond the tab — PWA manifest and the Ghost Log recap

Usability wave Workstream C (#5, #7):
- manifest.webmanifest with existing 192/512/180 icons, linked in
  index.html with theme-color aligned to #07070d; no service worker.
- GET /api/seances/recent: last 12 of the seeker's own séances with
  entity, per-kind event counts (one GROUP BY) and up to 3 spirit
  echoes (one windowed query) — no per-session N+1.
- /log Ghost Log page: cards with GhostGlyph, relative in-fiction
  timestamps, counts and echo lines; LOG link in the séance topbar;
  en/es i18n parity.

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

frontend/src/pages/SeancePage.tsx

@@ -264,6 +264,10 @@ function SeanceSession({ username }: { username: string }) {
             {t('nav.codex')}
           </Link>
 
+          <Link to="/log" className="seance-codex-link">
+            {t('nav.log', { defaultValue: 'log' })}
+          </Link>
+
           <Link to="/inventory" className="seance-codex-link">
             {t('nav.inventory', { defaultValue: 'inventory' })}
           </Link>