PR Summary: Add Model and Language Selectors for Nova Sonic

[alfonaws]

Issue #, if available:

Description of changes:

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[alfonaws]

Changes
Frontend (frontend/app/page.tsx)

Added model selector dropdown to choose between Nova Sonic (amazon.nova-sonic-v1:0) and Nova 2 Sonic (amazon.nova-2-sonic-v1:0)
Added language selector with support for 7 languages: English, Spanish, German, French, Italian, Portuguese, and Hindi
Both selectors are disabled when connected to prevent mid-session changes
Model and language are passed via WebSocket query parameters
Frontend (frontend/components/ui/select.tsx)

Created new Select component using Radix UI for the dropdowns
Backend (backend/main.py)

Updated WebSocket endpoint to accept model and language query parameters
Pass parameters to SimpleNovaSonic client on connection
Backend (backend/nova_sonic_simple.py)

Added language parameter to SimpleNovaSonic constructor
Updated system prompt to instruct the model to respond in the selected language
Dependencies

Added @radix-ui/react-select package
Housekeeping

Updated .gitignore with comprehensive patterns for Next.js, Python, and IDE files