V28: Burn Subtitles, Modern Editors, and Total Activity Control

Twenty-eight releases. Twenty-eight consecutive Fridays. V28 ships a burn-subtitles-into-video action right from the file context menu, so any video plus any caption file becomes a single video with the captions baked in. A universal Stop button on every activity card means you can cancel any running operation -- batch, conversion, export -- without hunting for the right dialog. Organize gets per-folder chips and workspace-root cross-folder selection so you can sweep a whole tree in one pass. Batch operations now show a per-file done, skipped, or failed chip so you always know exactly which files made it through. The preview three-dot menu has a new Copy Content item with keep-open and add-to-JSON modes -- pile content from many files into a single JSON without leaving the preview. Edit and move actions now check OS read-only permissions before they let you start, so you don't lose work to a permission denied at the end. The text, code, JSON, and markdown editors have been rebuilt on CodeMirror 6 for snappier typing, cleaner search, and better large-file handling. Long videos play more smoothly, the video editor is steadier, DOCX header and footer rendering is much better, and a long list of small Windows and shortcut fixes round it out.