Offering: Japanese locale completion — 1212 keys missing vs en.json (ready to ship)

Measured drift on : ja.json covers 928/2140 flat keys vs en.json — 1212 missing (43% coverage), the largest gap of any locale.

I've already prepared the full completion (branch on my fork, 2140/2140 parity, all placeholders preserved, existing translations untouched) and can open the PR immediately — but GitHub is currently rejecting my PR-creation calls on this repo, so offering here first.

Sample of what's filled: settings, authorization, documentation, inspections blocks — natural Japanese, tech terms (JWT/OAuth/API) kept per your existing style.

Free for the OSS repo; paid retainer available if you want automated locale-parity CI.