Add structured AI courseware APIs

添加持续对话功能：支持每个功能模块与AI进行多轮对话和互动

feat: 添加国际化、文件上传和专属聊天页面

fix: 修复 TeacherDashboard 运行时 Record 报错

fix: 添加错误边界和调试日志，更新页面标题为 ClareCourseWare

refactor: ClareCourseWare 教师专用 - 移除所有学生界面，登录后直接显示 TeacherDashboard；简化 App.tsx 为教师专用版本

feat(teacher): add reply language selector (zh/en/auto) + per-feature history (last 5); fix 4 issues: language control, history memory, 9 features layout

fix(teacher): split 9 features into 2 sections (基础建课 4项 + Courseware进阶 5项), show 共9项 in header

feat(teacher): add 5 courseware features to dashboard (vision, activities, copilot, qa-optimize, content); fix course description topic bug

fix: use SVG for other_format icon (build fix after LFS removal)

IST345 course + multi-TA, AI Quiz API doc, courseDirectory and sidebar updates

Add teacher agent, docs, and project updates; ClareVoiceV1 remains untracked (nested repo)

Add Clare product UI: run_web.sh, README, exclude hf_space from push