feat(ui): add macOS native binary direct download links

feat: complete removal of playwright from agent-node and re-align UI to prioritize standalone binary distro

Refactor AI Config and Fix Login failure: Migrated services to a structured api directory, updated backend schemas for multiple TTS/STT providers, and improved settings/chat UI coverage.

refactor(frontend): move shared components into shared/components

refactor(frontend): move nodes page and terminal into nodes feature module