fix(frontend): add safe-area-inset-top to SessionsHub for PWA mode

Adds env(safe-area-inset-top) offset to the SessionsHub header padding
and absolutely-positioned header buttons so the system status bar no
longer overlaps the app content in mobile PWA mode.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: dorlugasigal

src/frontend/src/components/SessionsHub/SessionsHub.module.css

@@ -8,7 +8,7 @@
 
 .header {
   position: relative;
-  padding: 20px 16px 12px;
+  padding: calc(20px + env(safe-area-inset-top, 0px)) 16px 12px;
   border-bottom: 1px solid var(--border);
   text-align: center;
 }
@@ -32,7 +32,7 @@
 
 .headerBtn {
   position: absolute;
-  top: 16px;
+  top: calc(16px + env(safe-area-inset-top, 0px));
   display: flex;
   align-items: center;
   justify-content: center;
@@ -64,7 +64,7 @@
 
 .themeBtn {
   position: absolute;
-  top: 16px;
+  top: calc(16px + env(safe-area-inset-top, 0px));
   right: 16px;
 }