feedback5: merge W5I — real i18n phase 1: shared/i18n.js (Chinese msgids, params, data names), English game texts from the official EN client data (data/i18n/en.json), the 中文 / English switch on the title screen and in 设置, title / lobby / room / settings converted, server toasts and ticker lines with msgid + params, tools/i18n.mjs, docs/I18N.md (PR #70's translations by @YuriRestia reused, credited)

Conflict: server/match/player/basics.js imports (W5G's checkNotOwned + W5I's msg / dn). data/i18n/en.json rebuilt on the merged data (tools/build-i18n.mjs --offline): the 自选 data adds texts of CN-only operators and modules the EN client lacks, so coverage is 97.6 % (skills 95.9, talents 95.1); the coverage floors in test/i18n-data.test.js and docs/I18N.md say so. Golden unchanged; i18n / lobby / match / ui suites 1144/1144 after the rebuild, i18n e2e 1/1.

docs/DATA.md

@@ -1,8 +1,11 @@
 # DATA.md — generated game data (`data/*.json`)
 
-All files in `data/` except `data/assets.json` are produced by **`node tools/build-data.mjs`** (task F1) from the
+All files in `data/` except `data/assets.json` and `data/i18n/` are produced by **`node tools/build-data.mjs`** (task F1) from the
 official zh_CN client data ([Kengxxiao/ArknightsGameData](https://github.com/Kengxxiao/ArknightsGameData)) joined
 with `docs/research/*.json`. Do not edit them by hand — change the build script and rebuild.
+`data/i18n/en.json` (the official English texts of these files by record id and field) is written by
+`node tools/build-i18n.mjs` — rerun it after a build that changes a text (docs/I18N.md §2; `test/i18n-data.test.js`
+fails while it is stale).
 `data/assets.json` is written by `tools/fetch-assets.mjs`, which keeps the current file rather than drop entries whose
 downloads failed on this machine unless `--allow-shrink` (or `--prune`) is passed (docs/ASSETS.md, DESIGN §21.25).