archive: add 32px content footer; date section as a bottom card; hide cam scrollbar

The archive content frame gets a 32px footer (reusing the live grid-bar look)
with a fullscreen button that expands the player + timeline. The sidebar date
section is now a bottom-anchored card (panel-2, bordered, rounded) holding the
date input above the inline calendar; the camera list fills the space above it
and its scrollbar is hidden (still scrollable). Calendar colours tweaked to sit
on the card.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/archive.html

@@ -23,11 +23,18 @@
           <div class="arch-cal" id="calendar"></div>
         </div>
       </aside>
-      <div class="arch-content">
+      <div class="arch-content" id="arch-content">
         <div class="player-wrap" id="player">
           <div class="hint">Кликните по таймлайну ниже, чтобы смотреть запись</div>
         </div>
         <div class="timeline" id="timeline"></div>
+        <footer class="grid-bar" id="arch-bar">
+          <div class="gb-left"></div>
+          <div class="gb-center"></div>
+          <div class="gb-right">
+            <button class="gb-btn" id="arch-fs" title="Полный экран" aria-label="Полный экран">⛶</button>
+          </div>
+        </footer>
       </div>
     </main>
   </div>