refactor: extract config.py, add burn_only, fix title_segments and font size

- Extract all path/API config to config.py (single source of truth)
- Add run.py / burn_only.py / run.bat / burn.bat entry points
- burn_only: skip transcription/subtitle gen, fast reburn existing SRTs
- Fix title_segments: use transcript keyword time for split point
- Fix subtitle: each overlapping title shows max title_duration (not full clip)
- Fix burn_only font size: default from 90 to 60
- Delete old run_lesson1.bat/py, temp debug scripts
- Update README, ARCHITECTURE, CHANGELOG, add USAGE.md

burn_only.py

@@ -0,0 +1,73 @@
+# -*- coding: utf-8 -*-
+"""
+快速烧录脚本 - 跳过所有转录/字幕生成步骤
+直接用已有的 clips + title.srt + content.srt 合并烧录
+
+用法:
+    python burn_only.py
+    python burn_only.py "D:\\path\\to\\output_dir"
+"""
+import sys
+import os
+
+# 导入统一配置
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+import config
+
+OUTPUT = config.OUTPUT
+if len(sys.argv) > 1:
+    OUTPUT = sys.argv[1]
+
+TITLE_SRT = os.path.join(OUTPUT, "subs", "v1_title.srt")
+CONTENT_SRT = os.path.join(OUTPUT, "subs", "v1_content.srt")
+CLIPS_DIR = os.path.join(OUTPUT, "intermediates")
+MERGED_PATH = os.path.join(OUTPUT, "concat_merged.mp4")
+
+print(f"[Fast Burn Mode]")
+print(f"Output: {OUTPUT}")
+print()
+
+# 检查必要文件
+if not os.path.exists(TITLE_SRT):
+    print(f"ERROR: title.srt not found\n{TITLE_SRT}")
+    sys.exit(1)
+if not os.path.exists(CONTENT_SRT):
+    print(f"ERROR: content.srt not found\n{CONTENT_SRT}")
+    sys.exit(1)
+
+# 导入 pipeline（src 目录）
+src_dir = os.path.join(os.path.dirname(os.path.abspath(__file__)), "src")
+sys.path.insert(0, src_dir)
+from core import Pipeline
+
+# 构造 minimal config（只需要 output_dir 和 video_params）
+pipeline_config = {
+    'output_dir': OUTPUT,
+    'clips': [],
+    'video_src': None,
+    'video_params': {},
+    'term_corrections': {},
+    'api_key': '',
+    'api_host': '',
+}
+
+pipeline = Pipeline(pipeline_config)
+
+# 合并视频（如需要）
+if os.path.exists(MERGED_PATH):
+    print(f"Found existing merged video: {MERGED_PATH}")
+    merged_path = MERGED_PATH
+else:
+    import glob
+    clip_files = sorted(glob.glob(os.path.join(CLIPS_DIR, "clip*.mp4")))
+    if not clip_files:
+        print(f"ERROR: No clip videos found\n{CLIPS_DIR}\\clip*.mp4")
+        sys.exit(1)
+    print(f"Merging {len(clip_files)} clips...")
+    merged_path = pipeline.step_merge(clip_files)
+    print(f"Merged: {merged_path}")
+
+# 烧录
+print("Burning subtitles...")
+final_path = pipeline.step_burn(merged_path, TITLE_SRT, CONTENT_SRT)
+print(f"\nDone: {final_path}")