Per-stage token usage

Read the usage notification at the end of each executed batch stage

Full batch runs, including a batch with one solution, print recorded model usage when precheck, discovery, planning, conversion, test, packaging, and cost estimation finish or fail. Info logging is sufficient; no additional usage switch is needed. Save the notifications with --log-file ./logs/batch.log.

Illustrative log excerpts, not measured migration results or current Azure prices:

✓ [orders] Planning finished. Model tokens: 24,000 (20,000 input + 4,000 output across 5 calls). Open report: .../planning-summary.md
✓ [orders] Deployment package finished. Model tokens: 0 (0 input + 0 output across 0 calls). Open report: .../manifest.md
[orders] Estimated Azure cost: CAD <amount>/month (canadacentral).
✓ [orders] Cost estimation finished. Model tokens: 0 (0 input + 0 output across 0 calls). Open report: .../azure-cost-estimate-<timestamp>.md
✗ [orders] Conversion failed: Policy validation failed. Model tokens: 0 (0 input + 0 output across 0 calls)

• Input tokens are recorded prompt/context usage; output tokens are recorded generated responses. Total is input plus output.
• Calls counts recorded model invocations, not Azure pricing HTTP requests. The report link opens stage evidence.
• Zero tokens for deterministic packaging and cost estimation is expected; it does not mean Azure hosting is free.
• Skipped stages print already complete; skipped; their reports show no new stage usage. Stages not reached after a failure have no completion notice. A hard crash may prevent final notifications and usage reports from being written.

Keep the per-solution and batch reports

reports/<solution-id>/token-usage.md
reports/<solution-id>/token-usage.json
reports/migration-batch-<timestamp>.md
reports/migration-batch-<timestamp>.json

These paths assume reportDirectory: ./reports. Reports record per-stage input, output, total tokens, calls, exact/estimated count quality, and model execution duration. The final batch summary gives aggregate tokens and calls. Per-solution usage files are replaced on the next attempt; preserve them with the timestamped batch reports when you need history. Resume totals cover this attempt, not all prior runs.