feat(ui): modernize image previews and analysis status flow

[KGFCH2]

1. Implemented a responsive Grid View for uploaded images using st.columns.
2. Replaced static st.spinner with interactive st.status indicators showing step-by-step progress (Uploading, Processing, Analyzing).
3. Refined main header styling with a centered layout and descriptive captions.

@fizaayesha You can close #38 issue after merging this PR.

[fizaayesha]

Please resolve merge conflicts @KGFCH2

[KGFCH2]

@fizaayesha Check it once...