docs: improve CLAUDE.md with dev rules, browser verification, and change checklist

docs: add CLAUDE.md with architecture guide and common commands

docs: add development mode startup instructions to README

fix: address critical and important issues from code review

docs: add Docker deployment and Electron desktop setup instructions

feat(electron): add desktop-pet Electron shell adapted from Star-Office-UI

feat(security): add production config validation with startup check

feat(docker): add two-stage pnpm Dockerfile and docker-compose.yml

feat(ui): add password-protected AssetSidebar with upload, AI gen, and reset tabs

feat(i18n): add asset drawer translations for 4 locales

feat(api): add Gemini config and async background generation endpoints

feat(api): add layout persistence, asset upload, and reset endpoints

feat(assets): add asset path utilities and password helpers

feat(sidebar): add 实验功能 collapsible accordion with AI装修 link

feat(phaser): wire guest animation, tint, subagent label, and effects into CharacterManager