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

.gitignore

@@ -0,0 +1,15 @@
+# 运行期数据：SQLite 库（含明文账号密码）、导入备份、调试快照
+data/
+*.db
+*.db-wal
+*.db-shm
+*.imported
+
+# 本地环境
+.env
+.venv/
+venv/
+__pycache__/
+*.py[cod]
+.playwright-mcp/
+node_modules/