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.js

@@ -208,6 +208,8 @@ export function feedProvenanceNote(layers = [], overall = null) {
     return `${s.name || s.id} is ${String(s.feedState).toUpperCase()}${extras ? ` (${extras})` : ''}`;
   });
   const body = bits.join('; ') || `${String(overall).toUpperCase()} feed`;
+  if (overall === 'partial')
+    return `${body}. Narrate that coverage is incomplete with any count; do not claim full coverage.`;
   return `${body}. Narrate that provenance with any count; do not describe this as live.`;
 }
 
@@ -254,3 +256,35 @@ export function viewStateLayerRow(layer, options) {
     lastUpdate: snap.lastUpdate,
   };
 }
+
+/**
+ * The feed state and up to two layer names of a provenance envelope that is
+ * not nominal, or null. Values stay English (`state` is a feed-state id,
+ * `names` are `layer.name`); the HUD translates them for display.
+ * @param {{ overall?: string|null, layers?: Array<object> }|null} envelope
+ * @returns {{ state: string, names: string[] }|null}
+ */
+export function provenanceTag(envelope) {
+  const overall = envelope?.overall;
+  if (!overall || overall === 'nominal' || overall === 'off') return null;
+  const names = (envelope.layers || [])
+    .filter(
+      (s) => s.feedState && s.feedState !== 'nominal' && s.feedState !== 'off',
+    )
+    .map((s) => String(s.name || s.id || 'LAYER'))
+    .slice(0, 2);
+  return { state: overall, names };
+}
+
+/**
+ * Require a matching feedState for warning states: a view that is not
+ * nominal falls back on a missing or different state.
+ * @param {{ feedState?: string|null }|null} response The proxy's reply.
+ * @param {{ overall?: string|null }|null} provenance The context's envelope.
+ * @returns {boolean}
+ */
+export function hudSummaryMatchesProvenance(response, provenance) {
+  const state = provenance?.overall;
+  if (!state || state === 'nominal' || state === 'off') return true;
+  return response?.feedState === state;
+}