dsh-cache-miss: DSH Web Plugin: Yellow Single-Line Prompt on Cache Miss

`dsh-cache-miss` is a DSH web plugin maintained by developer wefio, designed to address the difficulty of promptly locating cache misses during agent development. It belongs to the "Memory" category and is implemented purely on the front end without modifying source code. Directly below the assistant response in the first conversation turn, and only when a cache miss occurs, it renders a yellow notice containing idle duration, re-billed token count, cached token count, and time to first token (TTFT). This plugin helps developers debug long-context usage and optimize prompt caching strategies.