dsh-bisect-debug: DeepSeek Harness plugin for quickly locating bugs using binary search

# Introduction When troubleshooting bugs, the most time-consuming part is often not the fix itself, but locating the issue. "The bug is definitely in the current code, but I don't know which section." "A 405 error occurs when clicking authorization, and it is unclear whether the blame lies with the frontend, gateway, or downstream API." "It was working fine last week, but I don't know which commit broke it." Facing such problems, relying on reading through code or guessing by experience is inefficient and often leads to random, ineffective adjustments. Binary search is the standard approach to handling such issues: halving the search range in each round allows for convergence to a specific function, boundary, or commit within just a few iterations. `dsh-bisect-debug` is a DeepSeek Harness (DSH) workflow plugin that encapsulates this method into an executable process. DSH's philosophy is "Everything is a plugin."