Remove film birds; fix language pill highlight

Strip every bird from the demo mockups: both hero video tabs and both
step-3 player scenes lose the background flock (.film-birds) and the
foreground flapping bird (.film-hero-bird), plus all related CSS in
styles/demo.css and the dead style.legacy.css.

Language selector: the <select> was 30px narrower than its pill, so in
appearance:base-select the click/focus highlight covered only the inner
~110px ("half the box"). Move the padding from the container onto the
control so it fills the pill edge-to-edge; mirror the fix in the mobile
legal.css override.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

website/styles/legal.css

@@ -120,7 +120,7 @@
         margin: 0;
     }
     .lang-select-container {
-        padding: 4px 10px;
+        padding: 0;
         gap: 4px;
     }
     .lang-select-container .globe-icon {
@@ -129,7 +129,9 @@
     }
     .lang-dropdown {
         font-size: 0.7rem;
-        padding: 0 6px 0 0;
+        /* Padding on the control (not the container) so the highlight fills
+           the whole pill — matches the desktop rule in landing-controls.css. */
+        padding: 4px 24px 4px 10px;
     }
     .lang-select-container .chevron-icon {
         width: 10px;