feat(i18n): translate the whole interface

Mark every UI string the unmarked-text check reported (534) plus text it
cannot see (helpers, joined labels, runtime-built panels), and translate
the result to Spanish and Russian: 1,679 messages each.

- Kept on purpose, with the reason where the text lives: provider and
  product names, place and camera names, codes and units, dB values, the HUD
  terminal readouts, demo shot titles that saved projects look up by title,
  and text for AI tools and the voice model.
- Modules shared with the server or AI tools stay free of the i18n import
  (local msg); the wind reading and voice session stay English and are
  translated where the page shows them.
- npm test now runs the unmarked-text check.
- Fixes on the way: a duplicated radio privacy paragraph, the contact panel
  toggle saying Expand while open, the CSS filter mistaking & for CSS.

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

docs/CURRENT-STATE.md

@@ -3030,8 +3030,11 @@ Shipped locales: **en** (source and fallback), **es** and **ru**. The code lives
 - **Not translated by design:** layer ids, share-link and hash parameters, API
   fields, voice tool schemas, provider names, feed data (callsigns, vessel and
   station names) and attribution.
-- **Gaps.** Strings added after #601's extraction (for example the Street Level
-  panel) are still raw English; there is no lint for unmarked UI text yet.
+- **Unmarked text.** The same check lists UI text that is not marked at all
+  (markup without `data-i18n*`, literals reaching the page without `t`/`tn`/`msg`)
+  and fails on it. Text kept on purpose says why: `translate="no"`,
+  `data-i18n-runtime`, or `// i18n-ignore: <reason>`. `src/tools/` is skipped:
+  it writes for AI clients, not the page.
 
 ## Canonical Docs Order