feat(pets): implement strict pets management ui, i18n translations and pipeline validations

[CFBruna]

What Changed

• Resolved React Router 404 bug by properly mapping the admin/pets path under the correct root lazy import in main.tsx.
• Refactored PetViewSet in backend to remove disabled pagination, allowing proper List/Search fetching for Pets via API.
• Introduced a unified standalone CustomerSelectField component nested in PetModal with integrated Search Debouncing and Quick Registration (via modal trigger).
• Enforced complete i18n translation parity (PT, EN, ES) eliminating any explicit text fallback violations and missing validation keys.
• Applied "Read-Only/View" lock mode to Pets tabular UI to protect row data from accidental edits.
• Addressed all verificacao-uv.md compliance targets: completely resolving React strict mode useEffect cascading re-renders and completing Prettier/Linter formats on the frontend stack.

Why

The previous implementation of the Pets administrative screen was inaccessible from the sidebar, failed to display results due to malformed list structures, lacked Spanish/English translations (violating core standards), and required stringent data encapsulation tests (mypy, ruff, bandit, eslint) to be fully approved before merging.

How to Test

• Initialize backend with uv run python src/manage.py runserver and frontend with npm run dev.
• Navigate to the Pets section in the Administration Sidebar; interact with the Table to open the new View Mode and use the Pencil icon to trigger Edit.
• Ensure the Owner selection dropdown appropriately fetches customers in real-time or allows you to spawn the Quick Creation floating modal.
• Verify that npm run lint, npm run build and uv run pytest all finish without any degradation flags.

Checklist

• Service layer architecture followed
• No ORM in views
• No hardcoded strings (frontend and backend)
• Translation keys added to en, pt, es
• Tests added or updated
• uv run pytest passes
• npm run build passes
• Turing Test passed (works with PYG .env)