v0.4.0

Summary

• Fix streaming usage under-reporting (auto stream_options.include_usage for OpenAI-compatible streams; merge Anthropic SSE usage)
• SQLite WAL mode with batched writes (~200ms / 50 records)
• Per-customer spend allowances with 429/402 enforcement
• Optional X-Call-Id / X-Step, X-Unit-Id, and retry correlation (X-Correlation-Id / X-Attempt)
• Dashboard: step drill-down, cost-per-unit, waste spend metric

Package: llm-agent-metering==0.4.0