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/static/app.js

@@ -1047,6 +1047,9 @@ const Archive = {
     this.bindCalendar();
     this.renderCalendar();
 
+    const fsBtn = document.getElementById("arch-fs");
+    if (fsBtn) fsBtn.onclick = (e) => { e.preventDefault(); toggleFullscreen(document.getElementById("arch-content")); };
+
     // при ресайзе окна пересчитать смещение ленты (центр зависит от ширины вьюпорта)
     window.addEventListener("resize", () => { if (this.track) this._applyTl(); });