Network compliance landscape

The free compliance landscape (issue #692): per-country error rates — the share of a country's registered participants that break at least one published Peppol rule — and the per-rule breakdown of every open finding. Counts ONLY: no participant, seat or hostname appears here; the participant-level records are GET /v1/compliance/findings (Network tier). Read from the pre-computed compliance rollup tables and edge-cached. Keyless-cacheable.

Pass country to scope the whole body to one country (issue #716): the same shape, with countries holding that one cell, rules its own breakdown, each rule's share a share of THAT country's open findings, and the code echoed back in country. A country scope is how a structural national pattern is told apart from a real problem — AU and NZ, for example, break not_in_peppol_directory almost everywhere because A-NZ PINT participants are absent from the European Peppol Directory by design.