Refactor app navigation with route based workflows and stepper support

[Irozuku]

Summary

Refactored the Datasets, Models, and Generative modules to use URL-based routing instead of local component state for navigation and workflow management. This enables deep-linking, improves browser navigation, simplifies component logic, and provides a more consistent user experience. Additionally, stepper navigation was added to multi-step workflows, allowing users to move backward during dataset uploads and session creation flows.

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Type of Change

Check all that apply like this [x]:

• Backend change
• Frontend change
• CI / Workflow change
• Build / Packaging change
• Bug fix
• Documentation

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Changes (by file)

• src/App.jsx: Added granular route definitions for datasets, notebooks, models, and generative sessions, enabling direct navigation to specific resources and actions.
• src/pages/Datasets/*: Refactored dataset and notebook workflows to use route-based navigation and added stepper navigation for dataset upload flows.
• src/pages/Models/ModelCenterContent.jsx: Migrated model navigation and session workflows from local state to URL-based routing.
• src/pages/Models/CreateSessionSteps.jsx: Derived the active step from the current route and integrated stepper navigation for session creation.
• src/pages/Generative/SelectTaskMenu.jsx: Replaced local step management with route-driven navigation.
• src/pages/Generative/SelectModelMenu.jsx: Updated model selection to navigate using routes.
• src/pages/Generative/SessionBar.jsx: Refactored session creation and deletion flows to use route navigation.
• src/pages/Generative/CreateSessionSteps.jsx: Added stepper navigation to support backward navigation during generative session creation.
• src/components/GenerativeBreadcrumbs.jsx: Added contextual breadcrumbs for the Generative module.
• src/components/ModelsBreadcrumbs.jsx: Added contextual breadcrumbs for the Models module.

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Testing (optional)

• Verify direct navigation to datasets, notebooks, models, and generative sessions via URL.
• Confirm browser back/forward navigation works correctly across all modules.
• Validate that steppers allow backward navigation during dataset uploads and session creation workflows.
• Ensure session and dataset creation/deletion redirects to the appropriate routes.
• Confirm breadcrumbs accurately reflect the current route and support navigation to parent views.