dsh-mcp-adapter: Enables DeepSeek Harness to invoke MCP on demand instead of injecting all schemas into the context

# Introduction Connecting MCP servers to DeepSeek Harness (hereinafter referred to as dsh) is most directly achieved via the official `@deepseek-ai/dsh-mcp-client`. This client connects to the server at startup and registers each declared tool as a native `mcp__<server>__<tool>` function. The trade-off is the schema cost: with multiple servers, hundreds of tool definitions are passed into the context with every request, regardless of whether they are utilized. `dsh-mcp-adapter` provides an alternative solution to this problem by registering only a single `mcp` proxy tool. It employs lazy server startup, allowing the model to `search` or `describe` tools on demand.