dsh-usage-record: Add a question navigation rail to the DSH Web chat area

# Introduction When using DSH Web for long conversations, a common annoyance is the difficulty of revisiting a previous query. Because the chat area uses virtualized rendering, scrolling past a section means earlier content isn't loaded yet, so scrolling back requires waiting. The left sidebar session list is cluttered with "new sessions," making it hard to distinguish between them based solely on titles. dsh-usage-record addresses these two issues: it adds a vertical navigation rail to the left of the chat area, where each line corresponds to a prompt, and clicking jumps directly to it. It also automatically generates session titles based on prompt content. The following sections introduce its features, installation, and precautions. # What is it? dsh-usage-record is a DSH client plugin (web platform only) maintained by kkishapppy.