cleanup: remove dead code and duplicate docs

- Remove session-ses_2f27.md (161KB raw session log)
- Remove 49 ROOT_* duplicate files across REFERENCE/
- Remove 14 duplicate files between REFERENCE/ root and history/
- Remove asr_legacy.rs (dead code, replaced by asr.rs)
- Remove src/core/worker/ (duplicate JobWorker)
- Remove src/core/layers/ (empty directory)
- Remove 4 .bak files in src/
- Remove 7 dead private methods in worker/processor.rs
- Remove backup directory from git tracking

portal/src-tauri/src/main.rs

@@ -74,6 +74,7 @@ fn main() {
             api::video::get_videos,
             api::video::get_video_faces,
             api::video::get_chunk_detail,
+            api::video::unregister_video,
             api::person::get_person_thumbnail,
             api::person::get_person_thumbnail_b64,
             api::translation::translate_text,