feat(mobile): Professional Mobile App Logo Booting Animation (#11)

[Vishal-770]

Description

Fixes #11.

Changes Included

1. App Logo Booting Animation & Theme Sync (index.html, src/App.css, src/pages-mobile/_app.tsx):

   • Added a zero-latency native-feeling embedded boot splash overlay displaying the app logo (public/logo.png).
   • Integrated synchronous early theme detection in index.html to eliminate dark/light mode flashing during startup.
   • Clean, professional breathing opacity pulse animation (2.4s ease-in-out opacity pulse).
   • Smooth 300ms hand-off fade-out transition upon React mount.

2. Attendance Detail Retry Button & Skeleton Fix (src/pages-mobile/dashboard/attendance/[classId].tsx, src/pages-desktop/dashboard/attendance/[classId].tsx):

   • Fixed the retry button dimensions (min-w-[144px] h-9) so it maintains consistent layout regardless of state (Retry Connection, Connecting..., Offline).
   • Disabled retry button when offline to prevent continuous click spam.
   • Separated manual retry loading state from global skeleton loader to eliminate flickering.

Verification

• Tested build using npx tsc --noEmit (0 errors).

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