chore(miner-selfimprove): scaffold packages/gittensory-miner calibration module directory + shared types

[JSONbored]

The calibration-report, prediction-ledger, and metrics-exporter issues in this phase all live under a new packages/gittensory-miner/src/calibration/ subtree. Scaffold the directory, shared TypeScript types, and package-level wiring FIRST so those issues can land independently without each one re-deciding the module boundary — pure structural/mechanical setup, no calibration logic itself.

Deliverables

• Create packages/gittensory-miner/src/calibration/types.ts defining the shared PredictedVerdictRecord, ObservedOutcomeRecord, and CalibrationReport/CalibrationRow shapes (mirroring GateEvalReport/GateEvalRow's field names from src/review/parity.ts for easy mental mapping, without importing it directly)
• A barrel packages/gittensory-miner/src/calibration/index.ts re-exporting the module's public surface
• Wire the new subtree into the package's existing tsconfig/build script (mirror packages/gittensory-mcp's node --check-style build step) and its published-files list if calibration output is meant to be user-facing CLI output
• A placeholder unit test file (packages/gittensory-miner/test/calibration/types.test.ts or equivalent) asserting the shared types compile and satisfy a minimal fixture, so the directory isn't merged empty
• No calibration logic in this PR — types + scaffolding only; the report/ledger/metrics issues above build ON this

References

• packages/gittensory-mcp/package.json — the sibling package's exact packaging convention (tsconfig, build script, files list, bin shebang pattern) this scaffold copies
• src/review/parity.ts (301 lines) — GateEvalReport/GateEvalRow, the field-naming reference for the new shared types
• New path: packages/gittensory-miner/src/calibration/ (the directory this issue creates)

[linear-code]

JSO-2429