dsh-code-review: Open git diff as a standalone Code Review page

`yangzhe1991/dsh-code-review` is a code review plugin (MIT License) developed specifically for DSH Web sessions. It aims to address the inconvenience of viewing `git diff` in the chat window; when diff code blocks or bash tool lines appear in a session, it provides an "Open in New Tab" button to render the diff into a standalone code review page. Key features include supporting two-column side-by-side views to clearly display differences between old and new files, featuring line numbers, character-level highlighting, and basic syntax highlighting (keywords, strings, etc.), preserving `@@` hunk separators and multi-file block display, and offering a file navigation sidebar and a top statistics bar. The review page inherits DSH theme colors, supports light/dark mode and both Chinese and English interfaces. Users can add inline comments at line numbers and submit them automatically after...