fix(hud): lead with the state tag, keep feedState in get_hud_caption

Review fixes for the HUD summary language change:

- The translated feed-state tag now leads the one-line summary and the
  fallback line, so the readout's ellipsis cannot hide it.
- get_hud_caption checks the reply's feedState, returns it and appends the
  state tag; a reply naming another state keeps only the place.
- The model gets the layer names the user sees (localizeLayerName).
- Japanese and Chinese summaries are capped at 20 characters; pt, zh-CN and
  zh-Hant get explicit language names.
- A partial view is narrated as incomplete coverage, not as not live.
- provenanceTag and hudSummaryMatchesProvenance move to layerSnapshot.js so
  the tools package can use them without browser globals.
- docs/CURRENT-STATE.md, changelog and comments updated; redundant tests
  trimmed.

src/data/layerSnapshot.test.mjs

@@ -132,6 +132,9 @@ test('partial is a feed-state of its own: above nominal, below every fault', ()
   assert.equal(overall([partial, stale]), 'stale');
   assert.equal(overall([stale, partial]), 'stale');
   assert.equal(LAYER_FEED_STATE_LABELS.partial, 'PARTIAL');
+  const note = feedProvenanceEnvelope([partial], { now: NOW }).note;
+  assert.match(note, /coverage is incomplete/);
+  assert.doesNotMatch(note, /do not describe this as live/);
   assert.equal(
     FEED_STATE_SEVERITY.fallback < FEED_STATE_SEVERITY.partial &&
       FEED_STATE_SEVERITY.partial < FEED_STATE_SEVERITY.nominal,