fix(proxy): architectural overhaul for timeouts, 9k limits, and infinite hang prevention

fix: change rate limit cooldown from 5 minutes to UTC midnight

refactor: remove manual XML parser to support native Cloudflare tools and implement sequential account rotation

feat: set kimi-k2.6 as default model in mock models response

fix: mock /v1/models response to bypass Cloudflare 405 Method Not Allowed error