Replace fmt.Errorf with a local testErr type to eliminate the banned fmt import. The type carries its own usage example comment per AX Principle 2. Co-Authored-By: Charon <charon@lethean.io>
Reliability fixes: - Fix HTTP response body drainage in xmrig, ttminer, miner - Fix database init race condition (nil before close) - Fix empty minerType bug in P2P StartMinerPayload - Add context timeout to InsertHashratePoint (5s default) Architecture improvements: - Extract HashrateStore interface with DefaultStore/NopStore - Create ServiceContainer for centralized initialization - Extract protocol response handler (ValidateResponse, ParseResponse) - Create generic FileRepository[T] with atomic writes 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
