dsh-llm-qoder: A plugin to route DSH's LLM interface to the local Qoder CLI

`dsh-llm-qoder` is a DeepSeek Harness (DSH) plugin designed to enable DSH to directly reuse the local `qodercli` login session, thereby eliminating the need to configure API keys or settings. The plugin registers two provider routes, `qoder` and `qoder-byok`, supporting out-of-the-box access, persistent session management (based on LRU eviction), bridging host tools to the inner model via MCP, real-time fetching of model directories (with a fallback to static directories upon failure), and dynamic switching of context windows and thinking intensity. Furthermore, it supports cold-start calls for bypass requests and maps exceeded context windows to `CONTEXT_WINDOW_EXCEEDED` to trigger an overflow recovery mechanism.