fix: tab bar fills iOS home-indicator zone (no empty band below icons)

Switch the mobile #chat shell from 100dvh to full-height (100vh/100lvh)
and pad the tab bar by env(safe-area-inset-bottom) so the bar reaches the
physical bottom and its icons sit above the home indicator — instead of
leaving a same-color band below the icons. Keyboard-pinning path
(body.kb #chat) unchanged. Per building-ios-pwas skill; needs on-device
verification.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01G796GsLCvJQKVN7hwV2cDx

lyra/web/static/style.css

@@ -837,8 +837,9 @@ select:hover {
     position: fixed;
     top: 0; left: 0; right: 0;
     width: 100%;
-    height: 100dvh;     /* the *visible* viewport (excludes the home-indicator zone);
-                           overrides the base 95vh. Body bg matches the bar below it. */
+    height: 100vh;      /* full physical screen (incl. home-indicator zone) so the
+                           tab bar can fill that zone instead of leaving an empty band */
+    height: 100lvh;     /* explicit: largest viewport == physical screen */
     background: var(--bg-dark);
     border-radius: 0;
     border: none;
@@ -923,7 +924,9 @@ select:hover {
     flex: none;          /* never let it be compressed/clipped by the flex column */
     border-top: 1px solid var(--border);
     background: var(--bg-elev);
-    padding-bottom: 6px;  /* 100dvh already excludes the home-indicator zone */
+    /* shell is full-height (100vh), so the bar reaches the physical bottom; pad its
+       icons up above the home indicator and let its bg fill the inset zone. */
+    padding-bottom: calc(6px + env(safe-area-inset-bottom));
     padding-left: env(safe-area-inset-left);
     padding-right: env(safe-area-inset-right);
   }