Add comprehensive unit tests for Angular components and services

[devin-ai-integration]

Summary

This PR adds 33 new unit tests across multiple Angular components and services, increasing total test count from 16 to 49. The changes also fix existing import path bugs and add CI-compatible Karma configuration.

New tests added:

• ItemComponent: Tests for @input properties (name, description, price) and the like() method
• UsersServices: HTTP call tests using HttpTestingController with proper mocking
• AddItemComponent: Individual field validation tests and form initialization tests
• AppRoutingModule: Route configuration tests for shop, users, and default redirect

Bug fixes:

• Fixed incorrect import paths: changed src/app/users/... to src/app/user/... in three files (the directory is singular "user" not "users")

Configuration:

• Added ChromeHeadlessCI custom launcher in karma.conf.js for CI environments

Review & Testing Checklist for Human

• Verify import path fixes are correct: The original code had users (plural) but the actual directory is user (singular). Check that src/app/user/application/UsersServices is the correct path.
• Review package-lock.json changes: The lockfileVersion changed from 2 to 1 - verify this is acceptable or revert if unintended.
• Run tests locally: Execute npm test to verify all 49 tests pass in your environment.
• Verify CI compatibility: Ensure the ChromeHeadlessCI configuration works in your CI pipeline.

Recommended test plan:

1. Run npm test -- --no-watch --browsers=ChromeHeadless locally
2. Verify the application still builds with npm run build
3. Check that CI passes after merge

Notes

• The tests use standard Angular testing patterns (TestBed, HttpTestingController, spyOn)
• Material component warnings in test output are expected since test modules don't import all Material modules
• The UsersServices tests don't include HTTP error handling scenarios - this could be added in a follow-up

Link to Devin run: https://app.devin.ai/sessions/3ab7ecbe9e794edca995ac6f6cc057b5
Requested by: @milind-cognition

[devin-ai-integration]

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