emrg: gui renderer Batch 1 remainder — i18n full dictionary (373 keys) + markdown port

[argszero]

Summary

Batch 1 remainder of the GUI renderer React migration (design ~/.emrg/designs/gui-react-migration-design.md §5, rant 2026-08-26T12:16:48 — Batch 1 items 3 + 5). Completes the pure-logic port layer after #992 (commands/copywriting + preload API-surface guard).

1. i18n — full dictionary + vanilla logic port

• src/lib/i18n-dicts.ts (auto-generated from vanilla renderer/js/i18n.js): full 373-key zh/en dictionaries, strict parity (guarded by test).
• src/lib/i18n.tsx upgraded from Batch-0 skeleton to the full implementation:
  • detectLocale() (navigator, zh* → zh), getLocale()/setLocale() (localStorage emrg.locale override, "" = follow system), t(key, params) with zh fallback + {var} interpolation — semantics identical to vanilla.
  • React-shell-only keys (shell.batch0Notice etc.) kept as a provider-level extension so the vanilla dict stays pure.
• Tests +11 (i18n.test.ts): mirror the old emrg/gui/test/i18n.test.js node:test assertions (detectLocale / en-zh strings / setLocale persistence / interpolation / unknown-key) + dictionary parity guard (373 keys aligned, no drift).

2. markdown — port with injectable vendor deps

• src/lib/markdown.ts: createMarkdownRenderer({ marked, DOMPurify, hljs, t }) returns renderMarkdown / streamProject / streamFinalize — ports the vanilla marked-v12 code renderer (hljs exact-lang highlight, auto fallback), DOMPurify sanitize, the block-projection streaming logic (stable blocks cached, live tail block re-rendered, unclosed fence → plain text, FENCE_END_RE / isFenceClosed exported pure).
• Key difference from vanilla: vendor deps are constructor-injected instead of read from window — testable in Vitest, wired to the browser entry when Batch 2 (chat) lands.
• Tests +11 (markdown.test.ts): fence open/closed dual-state, no-marked escape fallback, fake-marked render + DOMPurify sanitize, hljs highlight path, copy-button i18n, block-projection DOM structure (jsdom).

Verification (all green)

• renderer: npm run typecheck clean; npm test56/56 (was 34; +11 i18n +11 markdown)
• gui: npm test 265 (257 pass + 8 skipped, 0 fail)
• pytest: 1094 passed / 1 skipped; doc-count guard 4/4; import + CLI OK
• Agent.md count sync (renderer vitest 34 → 56)

Vanilla files (js/i18n.js, js/markdown.js) stay untouched until Batch 5 switch (design D3).

[argszero]

✅ LGTM — cycle cyc20260826-140537 (1/3)

Verified this cycle:

• Head 507977a unchanged since submission; PR MERGEABLE
• CI green: test + test-windows pass (run 32936239914)
• Diff review: 6 files / +1324 — i18n-dicts.ts full 373-key zh/en dict (mechanical generation, parity-guarded), i18n.tsx vanilla locale-logic port (detectLocale/getLocale/setLocale/t with zh fallback), markdown.ts injectable marked/DOMPurify/hljs wrapper with block-projection streaming, +22 vitest (i18n 11 + markdown 11)
• Agent.md count sync (renderer vitest 34→56)

Batch 1 remainder ready for merge once 3 consecutive LGTMs accumulate.

[argszero]

✅ LGTM — cycle cyc20260826-141311 (2/3)

Re-verified this cycle:

• Head 507977a unchanged since submission; PR MERGEABLE / CLEAN
• CI still green: test + test-windows pass (run 32936239914)
• Diff unchanged (6 files / +1324); i18n full-dict + markdown port remain sound

Consecutive LGTMs so far: cyc20260826-140537 (1/3) → this cycle (2/3).

[argszero]

✅ LGTM — cycle cyc20260826-141945 (3/3)

Re-verified this cycle:

• Head 507977a unchanged; mergeStateStatus CLEAN / MERGEABLE
• CI still green: test + test-windows pass (run 32936239914)
• Diff unchanged (6 files / +1324)

3 consecutive LGTMs from different cycles (140537 → 141311 → 141945), no ❌ in between. Merge condition satisfied.