Replace rich SPM provenance with compact typed receipts

[anth-volk]

Fixes #3862

Summary

• replaces rich country-package SPM diagnostic payloads with strict compact canonical-spm-provenance-v2 receipts
• exposes spm_provenance as the sole completed-result SPM metadata field and rejects the removed sibling spm_config
• derives the internal resolved SPM configuration from the receipt when validating request identity
• adds typed comparison receipts with one receipt and execution count per baseline/reform side
• types Stage 12 simulation artifact provenance as the compact receipt itself
• requires four explicit non-empty runtime package versions
• bumps household, economy, and report cache identities so old payloads miss and recalculate instead of being translated
• publishes the exact contracts in OpenAPI and documents the breaking response change

API behavior

Existing Flask/API v1 household, economy, and report routes remain in place. Request-side partial SPM selections are unchanged. Successful canonical household results expose one compact spm_provenance receipt. Completed US society-wide results expose one compact comparison receipt in spm_provenance. Completed US economy report updates require valid compact provenance and reject the removed spm_config field before persistence. Historical dual-field or incompatible cached output is recalculated rather than translated. Numerical calculation results and route locations do not change; non-US report outputs are unaffected.

Validation

• full configured repository suite: 2,300 passed, 45 skipped
• real Redis cache integration: 6 passed
• focused completed-report, SPM, Stage 12, and OpenAPI suites
• uv run --frozen --extra dev mypy
• python scripts/export_migration_contracts.py
• python scripts/run_quality_guards.py
• Ruff and formatting checks on changed Python files

[codecov]

Codecov Report

❌ Patch coverage is 80.70866% with 49 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.55%. Comparing base (0ebfc08) to head (5f35197).

Files with missing lines	Patch %	Lines
policyengine_api/spm.py	84.12%	10 Missing and 10 partials ⚠️
policyengine_api/services/report_output_service.py	57.14%	12 Missing and 3 partials ⚠️
...engine_api/runtime_cache/household_calculations.py	78.26%	2 Missing and 3 partials ⚠️
...gine_api/services/household_calculation_service.py	71.42%	2 Missing and 2 partials ⚠️
policyengine_api/services/simulation_service.py	91.66%	2 Missing ⚠️
policyengine_api/worker_spm.py	80.00%	1 Missing and 1 partial ⚠️
policyengine_api/services/v2/reports/types.py	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #3863       +/-   ##
===========================================
+ Coverage   45.76%   87.55%   +41.79%     
===========================================
  Files         182      197       +15     
  Lines       10812    12153     +1341     
  Branches     1837     2145      +308     
===========================================
+ Hits         4948    10641     +5693     
+ Misses       5456      920     -4536     
- Partials      408      592      +184     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[anth-volk]

Closing as superseded: these changes were incorporated into and deployed through #3855.