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/voice/control.js

@@ -14,14 +14,14 @@ export function createVoiceControl({ reset = false } = {}) {
     root.dataset.speaker = 'idle';
     root.innerHTML = `
       <div class="gev-voice-heading">
-        <div class="gev-voice-kicker">${t('setup.voice.kicker.agent')}</div>
-        <div id="gev-voice-status">${t('setup.voice.status.idle')}</div>
+        <div class="gev-voice-kicker">${t('AI AGENT')}</div>
+        <div id="gev-voice-status">${t('OFF')}</div>
         <div class="gev-voice-cost">
-          <button id="gev-voice-tier" class="gev-voice-tier-btn" type="button" aria-pressed="false" title="${t('setup.voice.tier.buttonTitle')}">STD</button>
-          <span id="gev-voice-cost-value" class="gev-voice-cost-value" data-level="ok" title="${t('setup.voice.cost.buttonTitle')}">~$0.00</span>
+          <button id="gev-voice-tier" class="gev-voice-tier-btn" type="button" aria-pressed="false" title="${t('Voice model tier — applies next session')}">STD</button>
+          <span id="gev-voice-cost-value" class="gev-voice-cost-value" data-level="ok" title="${t('Estimated session cost')}">~$0.00</span>
         </div>
       </div>
-      <button id="gev-voice-button" type="button" aria-label="${t('setup.voice.button.ariaLabel')}" aria-describedby="gev-voice-help">
+      <button id="gev-voice-button" type="button" aria-label="${t('Voice control — activate to toggle voice; hold Space to speak')}" aria-describedby="gev-voice-help">
         <span class="gev-mic-orbit"><img src="/mic.svg" alt="" /></span>
         <span class="gev-mic-label">ON/OFF</span>
       </button>
@@ -29,11 +29,11 @@ export function createVoiceControl({ reset = false } = {}) {
         ${Array.from({ length: 15 }, (_, index) => `<span style="--bar:${index}"></span>`).join('')}
       </div>
       <div class="gev-voice-readout">
-        <div id="gev-voice-detail">${t('setup.voice.detail.standby')}</div>
+        <div id="gev-voice-detail">${t('VOICE STANDBY')}</div>
       </div>
       <div id="gev-voice-help" class="gev-voice-help-tray" role="tooltip">
-        <span class="gev-voice-help-kicker">${t('setup.voice.kicker.control')}</span>
-        <span class="gev-voice-help-detail">${t('setup.voice.hint.default')}</span>
+        <span class="gev-voice-help-kicker">${t('VOICE CONTROL')}</span>
+        <span class="gev-voice-help-detail">${t('Hold Space to speak · tap Space to activate focused controls')}</span>
       </div>
       <section id="gev-voice-card" class="gev-voice-card" hidden aria-label="Voice assistant">
         <div class="gev-voice-card-header">
@@ -59,11 +59,11 @@ export function createVoiceControl({ reset = false } = {}) {
       </section>
       <div class="gev-voice-error-tray" role="alert" aria-live="assertive">
         <div class="gev-voice-error-header">
-          <span>${t('setup.voice.error.trayTitle')}</span>
-          <button class="gev-voice-error-dismiss" type="button">${t('setup.voice.error.dismiss')}</button>
+          <span>${t('VOICE SYSTEM ERROR')}</span>
+          <button class="gev-voice-error-dismiss" type="button">${t('DISMISS')}</button>
         </div>
         <div id="gev-voice-error-detail"></div>
-        <div class="gev-voice-error-hint">${t('setup.voice.error.hint')}</div>
+        <div class="gev-voice-error-hint">${t('Check microphone permission and network access, then try again.')}</div>
       </div>
     `;
     const commandDock = document.getElementById('command-dock');