chore(angular-react): Migrate AddItemComponent to React

[devin-ai-integration]

chore(angular-react): Migrate AddItemComponent to React

Summary

This PR creates a React version of the Angular AddItemComponent form component, preserving all validation rules. The migration includes:

• New AddItemComponent.tsx with React hooks for form state management (useState, useMemo, useCallback)
• Form validation matching the Angular version: all three fields (name, description, price) are required
• Button disabled state when form is invalid
• onSaveItem callback prop for form submission
• Comprehensive test suite with 10 tests using React Testing Library

The original Angular component is intentionally preserved per migration guidelines.

Note: Angular Material styling is not ported - the React component uses plain HTML inputs. TODO comments document this for future work.

Review & Testing Checklist for Human

• Verify the validation logic matches Angular behavior: all fields required, button disabled when invalid
• Confirm the onSaveItem callback receives correct form data structure { name, description, price }
• Review the large dependency additions (React 19, Jest 30) - ensure these versions are acceptable for the project
• Run npx jest locally to verify tests pass in your environment

Recommended test plan:

1. Import and render AddItemComponent in a test page
2. Verify button is disabled with empty fields
3. Fill all fields and verify button enables
4. Click save and verify onSaveItem callback receives form data

Notes

• Angular component preserved at original location (not removed per playbook)
• Jest configuration added for React component testing alongside existing Karma setup
• Tests mirror the original Angular test cases for consistency

Link to Devin run: https://app.devin.ai/sessions/b934026c1c2d459dbe14bc9cd83c6cad
Requested by: @milind-cognition

[devin-ai-integration]

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