Round-6 follow-up: UX polish + client-IP fix

- Client IP: the compose caddy trusts X-Forwarded-For from private-range
  upstreams (trusted_proxies private_ranges), so the real client IP survives
  the host-caddy hop (it was logging the docker caddy hop 172.18.0.x for chat
  moderation and bucketing the gateway per-IP rate limiter on it). Correct and
  spoof-safe in both contours (prod has no host caddy); peerIP unit-tested.
- Ad banner gated off behind a compile-time SHOW_AD_BANNER=false (the if-branch,
  the AdBanner import and banner.ts are tree-shaken out of the prod bundle).
- Landing: the Telegram entry is just the 64px logo (clickable, no button/text).
- TG-fullscreen header: title + menu centred as a pair (hamburger right of the
  title), pinned to the bottom of the TG nav band.
- Edge-swipe back (Screen): a left-edge rightward drag navigates to back
  (touch/pen only, armed from <=24px; skipped inside Telegram).
- Chat soft-keyboard: a bottom-sheet Modal lifted above the keyboard by a
  visualViewport-driven transform (compositor-only, no page/sheet relayout).
  iOS-specific, needs on-device tuning; native resize=none awaits Capacitor.
- Tests: e2e for the in-game '✓ in friends' item and a board→board tile
  relocation; codec units for last_activity_unix + OutgoingRequestList.

Deferred to the next PR (agreed): #4 enrich the your-turn/game-end push; #5 hide
finished games from the lobby.

ui/src/Landing.svelte

@@ -74,9 +74,8 @@
     <h1>{about.title}</h1>
     <p class="tagline">{t('landing.tagline')}</p>
     {#if tgLink}
-      <a class="play" href={tgLink} target="_blank" rel="noopener noreferrer">
-        <img src="telegram-logo.svg" alt="" width="22" height="22" />
-        {t('landing.playTelegram')}
+      <a class="tg" href={tgLink} target="_blank" rel="noopener noreferrer" aria-label={t('landing.playTelegram')}>
+        <img src="telegram-logo.svg" alt="" width="64" height="64" />
       </a>
     {/if}
   </section>
@@ -192,21 +191,20 @@
     color: var(--text-muted);
     font-size: 1.05rem;
   }
-  .play {
+  /* The Telegram entry is just the bigger logo (no button chrome, no caption); the link
+     keeps an aria-label for assistive tech (Stage 17). */
+  .tg {
     align-self: center;
     display: inline-flex;
-    align-items: center;
-    gap: 9px;
-    padding: 12px 24px;
-    border-radius: var(--radius-sm);
-    font-weight: 700;
-    text-decoration: none;
-    background: var(--accent);
-    color: var(--accent-text);
-    margin-top: 6px;
+    margin-top: 8px;
+    border-radius: 50%;
   }
-  .play img {
+  .tg img {
     display: block;
+    transition: transform 0.12s ease;
+  }
+  .tg:hover img {
+    transform: scale(1.06);
   }
   .info {
     background: var(--surface-2);