feat: campaign narrative translated into all 10 locales, native-reviewed (#238)

[pshenok]

Part 2 of #238 (mechanism landed in #239). The 214 narrative+chrome keys now carry real translations in hi, uk, ru, de, fr, it, pt-BR, ko, zh, nep — the campaign's teaching spine finally reads in the player's language.

How it was built

Per-locale pipelines: translator → adversarial native reviewer (prompted as an engineer who plays games, told to refute) → fixes in place. Each language's register was derived from its own file — the ~700 existing keys are the style guide — so the campaign reads like the rest of that locale: hi keeps the Hinglish glossary, uk keeps «ти», ru keeps formal «вы», de keeps its English-tech-term conventions, etc.

The reviewers earned their keep: 126 defects fixed

Exactly the classes a machine translation ships:

• Meaning inversions: pt-BR "passou longe de" taught the opposite of "far past" in L24's premise; ru and uk independently rendered redundant nodes as "резервные копии" (data backups), rewriting the availability-zone lesson; fr "télécharger" read as download in the upload level; zh literal "快 N 倍" prescriptively means (N+1)× — rewrote into the unambiguous "X 的 N 倍" form so the multipliers match the ms figures beside them
• Register breaks: a तुम-imperative in hi's आप-register file, "la finanza" in it (reads as the fiscal police, not the finance dept), Lusitanian "vagas" for waves in pt-BR
• Grammar a native never writes: de transitive "verbluten", ko particles welded to em-dashes, nep ergative mismatches

Register decisions worth knowing

• hi keeps level titles English ("HELLO, GPU") — its trophies panel already cites them in English; uk/ru/ko/it/fr/pt-BR/zh/nep translate titles to match the same cross-references their achievements already carry in those languages. Both directions are consistency-correct per file.
• Also bound the three static briefing headers in index.html (Learn/Goals/Bonus) to their campaign_* keys — they were hardcoded EN and survived locale switches.

Verified independently of the agents

• Scope machine-checked: every changed hunk inside the two #238 blocks, key sets byte-identical (only values differ)
• 805/805 × 5, eslint 0
• Browser: hi/uk/ko/en briefings + level list render with zero raw keys, zero console errors (hi L22 screenshot verified — scenario, learn, goals all in register)
• ru/uk hand-reviewed by the maintainer-side reviewer on top of the agent pass

Out-of-scope finds (filing separately): it.js pre-existing inconsistency — traffic_inference says "INFERENZA" while chapter-5 keys use "INFERENCE", and some it achievement texts cite level titles in EN.