Add loading skeleton instead of blank screen during data fetch

[ionfwsrijan]

Currently when the app is fetching GitHub user data,
the content area appears blank until the API response
is received. This creates a poor user experience,
especially on slower connections.

Expected behavior: Show a skeleton loader or spinner
while data is being fetched.

Actual behavior: Blank white/dark area shown during loading.

This is a UI enhancement that would improve perceived
performance.

[ionfwsrijan]

Closing as this is outside current project scope.