feat: study modes (fast/parallel) and course-container completion fix

- settings: study.mode fast|normal and study.parallel 1-5

- normal mode: one headless browser per video, visibility keep-alive, auto-degrade when the platform enforces order

- report study/log/detail/save before isComplete; drop lastProgressTime on completion

- complete periodType 10/13 container nodes and recompute counters via PUT calFinalScore

- capture mode: POST /api/capture records all XHR/fetch including new tabs

- UI: study mode in settings, capture / stop-capture menu items

.env.example

@@ -0,0 +1,18 @@
+# 复制成 .env 后按需修改：cp .env.example .env
+# docker compose 会自动读取同目录的 .env
+
+# 远程访问令牌：非空时，页面和所有接口都要带 ?token=<值>（首次带参数访问会记住 cookie）。
+# 生成一个：python -c "import secrets;print(secrets.token_urlsafe(24))"
+AUTH_TOKEN=
+
+# 监听端口（宿主机）
+PORT=8848
+
+# 绑定地址：0.0.0.0 = 所有网卡（远程管理）；127.0.0.1 = 只允许本机 + 反代转发
+BIND_ADDR=0.0.0.0
+
+# 每个账号保留的运行日志行数 / 课程页快照条数
+RUN_LOG_KEEP=2000
+SNAPSHOT_KEEP=200
+
+TZ=Asia/Shanghai