docs: update read-only wording for archive upload in ui-spec and panduan

docs/ui-spec.md

@@ -250,7 +250,7 @@ create-form panel → responsive card grid of projects.
 | Name | text, autofocus, required | |
 | Label type | select: `bbox` (YOLO detect) / `polygon` (YOLO segment) | hint: *fixed once the first batch is merged* |
 | Val split — every Nth frame | number 0–50, default 5 | |
-| Video archive root | text, required, default from `video_root_default` | hint: layout `<date>/<batch>.mp4`, read-only |
+| Video archive root | text, required, default from `video_root_default` | hint: layout `<date>/<batch>.mp4`; written only by user-initiated uploads and date folders (REQ-178), nothing else |
 | Classes | repeatable rows: swatch + name + SAM3 prompt + remove | at least one row; blank names are dropped on submit; prompt defaults to the name |
 
 Actions: *Create project* (submits), *Cancel*, *Add class*.