feat: push deploy pipeline - auth, sidebar layout, ML artifacts, LFS

Notable changes:
- Add .gitattributes for LFS tracking on ML model artifacts
- Add AuthGuard to all protected routes + login/register/logout flow
- Add collapsible Sidebar replacing old Navbar
- Redesign MainLayout with sidebar + mobile header
- Add password show/hide toggle to AuthForm
- Add Logout button to MobileNav
- Update footer credit to ATLAS Project - Pijak x IBM SkillsBuild
- Update deploy.yml: generate ONNX in CI (vs HuggingFace download)
- Remove deprecated ML scripts (download/upload model .sh, .gitignore)
- Remove stale MEMORY.md
- Add ML model artifacts (TFLite, SavedModel, TFJS)
- Update notebook.ipynb training pipeline

Co-Authored-By: Claude <noreply@anthropic.com>

.gitattributes

@@ -0,0 +1,6 @@
+best_model/best_model.keras filter=lfs diff=lfs merge=lfs -text
+model/saved_model/variables/variables.data-00000-of-00001 filter=lfs diff=lfs merge=lfs -text
+model/tfjs_model/*.bin filter=lfs diff=lfs merge=lfs -text
+**/best_model.keras filter=lfs diff=lfs merge=lfs -text
+**/variables.data* filter=lfs diff=lfs merge=lfs -text
+**/tfjs_model/*.bin filter=lfs diff=lfs merge=lfs -text