dsh-cost-ledger: DSH Cross-Session Token Cost Ledger Plugin

`dsh-cost-ledger` is an MIT-licensed plugin for DeepSeek Harness (DSH) designed to address the lack of unified tracking for LLM token usage. The plugin achieves cross-session persistence using SQLite, automatically subscribes to `llm/stream` events, and records detailed metrics including input, output, cache, and costs. It features a built-in DeepSeek pricing model and supports custom price configuration. The plugin provides three Agent tools—`record_cost` (manual recording), `query_cost` (to query costs), and `set_budget` (to set budgets)—to facilitate usage monitoring and budget control. Installation requires Node.js ^22.19.0 or higher, via `dsh`...