Registry-readiness preflight for one passport.

Returns whether a passport would pass the EU DPP Registry's formal submission gate — { ready, findings[] }. This is the registry's mechanical pre-submission check, distinct from and complementary to the substantive /compliance verdict: a passport can be registry-ready yet not substantively compliant, and vice-versa.

Five formal checks, each carried on the standard ComplianceFinding shape with a REG-READY-* ruleId:

• REG-READY-MANDATORY — every mandatory field that applies to this battery type is present and approved (applicability-aware: a field that is not applicable to the battery's category is not counted as missing; an unknown-applicability field surfaces as a warning, not a block);
• REG-READY-FORMAT — filled fields are well-formed (types, enums, patterns, ranges);
• REG-READY-LINK — the passport's public link resolves (a live probe; on an unpublished passport this is an advisory warning rather than a block);
• REG-READY-GRANULARITY — the passport carries a serial number, since batteries register at item-level granularity (a missing serial is a block);
• REG-READY-COMMODITY — the product's commodity code (CN/TARIC) is well-formed where the category carries one; for batteries, which carry no commodity code, this is an advisory warning only, never a block.

ready is true only when there are zero critical findings. Battery passports only in this version; a non-battery passport returns ready: true with a single REG-READY-SCOPE warning.

Read-only; counts as one v1 passport read against the daily cap.