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
• validate complete schema 7 target identity while retaining schema 6 publication compatibility

Validation

• packages/microcosm-calibrate/tests — 222 passed
• packages/microcosm-data/tests — 346 passed, 2 skipped
• packages/microcosm-build/tests/test_uk_target_references.py — 13 passed
• Ruff lint and formatting 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