fix: Perfect invoice print - use specific selectors for app shell

Added specific selectors:
- #woonoow-admin-app header
- #woonoow-admin-app nav
- #woonoow-admin-app [data-submenubar]
- #woonoow-admin-app [data-bottomnav]

These target the exact WooNooW app elements that need hiding.

admin-spa/src/index.css

@@ -160,15 +160,15 @@
     display: none !important;
   }
 
-  /* Hide WooNooW app shell (nav, header, submenu, bottom nav, etc) */
+  /* Hide WooNooW app shell - all nav, header, submenu elements */
+  #woonoow-admin-app header,
+  #woonoow-admin-app nav,
+  #woonoow-admin-app [data-submenubar],
+  #woonoow-admin-app [data-bottomnav],
   .woonoow-app-header,
   .woonoow-topnav,
   .woonoow-bottom-nav,
   .woonoow-submenu,
-  nav,
-  header,
-  [data-nav],
-  [data-header],
   .no-print {
     display: none !important;
   }