dsh-workbuddy-xdpool: WorkBuddy Multi-Account Merged Pool

The `dsh-workbuddy-xdpool` plugin consolidates multiple accounts logged in to the WorkBuddy desktop app into a unified model pool. It supports automatic account merging, automatic failover to another account on 429 rate-limit errors, multiple allocation strategies, real-time credit monitoring, and automated actions (such as check-ins and reward collection). Users must first install and log in to WorkBuddy. The plugin is compatible with DSH 0.1.x and 0.2.0-rc.2, and is designed to simplify multi-account management.