Publish schema 7 geography dimensions

[anth-volk]

Summary

• publish schema 7 structured source, variable, and dimension identity for registry-backed releases
• publish geography dimensions and display metadata for UK and US builds
• preserve meaningful Ledger filters and non-geographic layout dimensions without duplicating values
• separate count and total measurements from their shared statistic category
• group UK OBR targets into EFO receipts and EFO expenditure categories declared by Microcosm
• publish source.label for every provider identifier in the current US and UK diagnostics surfaces
• keep the US and UK provider labels in separate immutable Microcosm mappings, outside Chronicle facts and target-reference metadata
• publish variable.label for every statistic category in the current US and UK diagnostics surfaces
• keep Level 2 labels in separate immutable country-and-provider mappings, including acronym-aware labels such as EFO, SPI, EITC, SSI, and CGT
• use the UK provider mapping for both schema 7 rows and release_manifest.publisher_labels
• validate complete schema 7 target identity and optional source and variable labels while retaining schema 6 publication compatibility

Validation

• packages/microcosm-calibrate/tests — passed
• packages/microcosm-data/tests/test_contract.py — passed
• packages/microcosm-build/tests/test_uk_diagnostics.py — passed
• packages/microcosm-build/tests/test_uk_release_assembler.py — passed
• US release diagnostics writer test — passed
• UK target-reference compilation and OBR categorization test — passed
• current US and UK Level 2 label coverage tests — passed
• Ruff lint checks
• generated a 364-target UK schema 7 preview with zero diagnostics-contract failures
• dashboard classified the preview release, rows, and dimension adapters as structured

Fixes #854