feat: replace karma by vitest

[n-elhk]

This PR migrates the test infrastructure from Karma + Jasmine to Vitest, aligning the project with modern Angular (v21) testing recommendations and significantly improving test performance and developer experience.

• Replace Karma & Jasmine with Vitest
• Use Angular’s @angular/build:unit-test builder
• Add Vitest configuration (vitest.config.ts)
• Migrate test setup and initialization to Vitest
• Replace Jasmine globals (describe, it, spyOn, etc.) with Vitest equivalents
• Configure code coverage (HTML + LCOV)
• Mock browser/WebGL-specific APIs where needed (e.g. MapLibre)
• Remove Karma-specific configuration and dependencies