Add filter management component tests

[JamBalaya56562]

Summary

• add Angular TestBed and Vitest coverage for the parent FiltersComponent
• verify exclude-all warning precedence and reactive updates
• verify bulk text conversion, normalization, filtering, and stable deduplication
• verify add, update, and remove collection operations without depending on jsdom scrolling

This is a test-only change. Production code, public APIs, dependencies, and lockfiles are unchanged. Child filter-row editing remains covered separately.

Validation

• bun install --frozen-lockfile
• bunx prettier --check projects/ngclient/src/app/backup/components/filters/filters.component.spec.ts
• targeted Angular/Vitest run: 13 tests passed
• bun run test:ci: 25 test files and 257 tests passed
• bun run gen:font
• bun run ng -- build ngclient --configuration production

Part of #273