refactor(i18n): key messages by English text; add Russian

Replace the semantic keys with the English source text, so code reads as the
UI does and English needs no catalog: t('Save keys'), tn(count, one, other)
for plurals, msg() for text stored in data, and bare data-i18n* markup that
translates the element's own English. Other languages are one flat JSON each.

- Simplify src/i18n: drop namespaces, the configurable locale pair
  (GEV_DEFAULT_LOCALE / GEV_SECONDARY_LOCALE) and its build defines. Locale
  comes from ?lang=, the stored choice, then browser languages.
- Add scripts/i18n.mjs (npm run i18n): extracts every message from t/tn/msg
  and markup, and fails on missing, unused, placeholder-mismatched or
  wrongly-shaped plural entries. npm test runs it via catalog.test.mjs.
- Add Russian (src/i18n/locales/ru.json, 833 messages), started from the
  community catalog in #312 and reviewed against the current English.
- Fix data-i18n placed on parents that would wipe their children (cockpit
  LEVEL and local weather cells, first-run EXPLORE MANUALLY tile), and a
  doubled degree sign in the TRACK ACQUIRED signal.
- Rewrite docs/TRANSLATORS.md for the new workflow; drop sections the earlier
  merge resurrected in docs/CURRENT-STATE.md.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/data/militaryAwarenessEngine.js

@@ -84,14 +84,14 @@ export function summarizeAwarenessCohort(
       relationship: AWARENESS_RELATIONSHIP.UNKNOWN,
       count: null,
       nearest: [],
-      reason: t('layers.awareness.reason.feedUnavailable'),
+      reason: t('feed unavailable'),
     };
   if (stale)
     return {
       relationship: AWARENESS_RELATIONSHIP.UNKNOWN,
       count: null,
       nearest: [],
-      reason: t('layers.awareness.reason.feedStale'),
+      reason: t('feed stale'),
     };
   const normalized = (Array.isArray(items) ? items : [])
     .filter(
@@ -108,8 +108,8 @@ export function summarizeAwarenessCohort(
     count: normalized.length,
     nearest: normalized.slice(0, limit),
     reason: normalized.length
-      ? t('layers.awareness.reason.nearby')
-      : t('layers.awareness.reason.none'),
+      ? t('observed or mapped nearby context')
+      : t('no observed or mapped objects in current feeds'),
   };
 }
 

src/data/satelliteClass.js

@@ -17,7 +17,7 @@
  * for), then the constellations users can actually name, then the grab-bag.
  */
 
-import { t } from '../i18n/index.js';
+import { t, msg } from '../i18n/index.js';
 
 /**
  * Class registry. `label` is the card/legend token, `color` the point color,
@@ -84,24 +84,26 @@ export const SATELLITE_CLASS_ORDER = Object.freeze([
 // translate through these keys at the presentation boundary.
 const CLASS_DISPLAY_KEYS = Object.freeze({
   station: Object.freeze({
-    label: 'layers.satellites.class.station',
-    blurb: 'layers.satellites.class.stationBlurb',
+    label: msg('STATION'),
+    blurb: msg('Crewed stations and their visiting vehicles'),
   }),
   nav: Object.freeze({
-    label: 'layers.satellites.class.nav',
-    blurb: 'layers.satellites.class.navBlurb',
+    label: msg('NAV'),
+    blurb: msg('GNSS navigation — GPS, GLONASS, Galileo'),
   }),
   geo: Object.freeze({
-    label: 'layers.satellites.class.geo',
-    blurb: 'layers.satellites.class.geoBlurb',
+    label: msg('GEO'),
+    blurb: msg(
+      'Geostationary belt — comms and weather, fixed over the equator',
+    ),
   }),
   visual: Object.freeze({
-    label: 'layers.satellites.class.visual',
-    blurb: 'layers.satellites.class.visualBlurb',
+    label: msg('VISUAL'),
+    blurb: msg('Brightest naked-eye objects — CelesTrak visual group'),
   }),
   comms: Object.freeze({
-    label: 'layers.satellites.class.comms',
-    blurb: 'layers.satellites.class.commsBlurb',
+    label: msg('COMMS'),
+    blurb: msg('Broadband constellation shell — shown only in DENSE mode'),
   }),
 });
 

src/data/vesselLabels.js

@@ -4,7 +4,7 @@
  * after the vessel cards moved out of their dedicated canvas renderer.
  */
 
-import { t } from '../i18n/index.js';
+import { t, msg } from '../i18n/index.js';
 
 export const VESSEL_OVERLAY_SOURCE_ID = 'ais-live-vessels';
 /** Existing selector grid size; one ambient winner is retained per cell. */
@@ -70,25 +70,25 @@ const NUMERIC_TYPE_FAMILIES = {
 // machine values — TYPE_STYLES matches on them and tests pin them — so card
 // text translates only through this map at the presentation boundary.
 const TYPE_DISPLAY_KEYS = Object.freeze({
-  FISHING: 'layers.vessel.type.fishing',
-  TOWING: 'layers.vessel.type.towing',
-  DREDGER: 'layers.vessel.type.dredger',
-  'DIVE OPS': 'layers.vessel.type.diveOps',
-  MILITARY: 'layers.vessel.type.military',
-  SAILING: 'layers.vessel.type.sailing',
-  PLEASURE: 'layers.vessel.type.pleasure',
-  PILOT: 'layers.vessel.type.pilot',
-  SAR: 'layers.vessel.type.sar',
-  TUG: 'layers.vessel.type.tug',
-  'PORT TENDER': 'layers.vessel.type.portTender',
-  'ANTI-POLLUTION': 'layers.vessel.type.antiPollution',
-  'LAW ENFORCE': 'layers.vessel.type.lawEnforce',
-  MEDICAL: 'layers.vessel.type.medical',
-  'HIGH-SPEED': 'layers.vessel.type.highSpeed',
-  PASSENGER: 'layers.vessel.type.passenger',
-  CARGO: 'layers.vessel.type.cargo',
-  TANKER: 'layers.vessel.type.tanker',
-  OTHER: 'layers.vessel.type.other',
+  FISHING: msg('FISHING'),
+  TOWING: msg('TOWING'),
+  DREDGER: msg('DREDGER'),
+  'DIVE OPS': msg('DIVE OPS'),
+  MILITARY: msg('MILITARY'),
+  SAILING: msg('SAILING'),
+  PLEASURE: msg('PLEASURE'),
+  PILOT: msg('PILOT'),
+  SAR: msg('SAR'),
+  TUG: msg('TUG'),
+  'PORT TENDER': msg('PORT TENDER'),
+  'ANTI-POLLUTION': msg('ANTI-POLLUTION'),
+  'LAW ENFORCE': msg('LAW ENFORCE'),
+  MEDICAL: msg('MEDICAL'),
+  'HIGH-SPEED': msg('HIGH-SPEED'),
+  PASSENGER: msg('PASSENGER'),
+  CARGO: msg('CARGO'),
+  TANKER: msg('TANKER'),
+  OTHER: msg('OTHER'),
 });
 
 /**