fix(hud): keep localized summary words whole and drop padding

- The proxy keeps combining marks, in-word apostrophes and name dots
  (ar vowel signs, fr d'Orléans, ja ・), normalizes to NFC, caps every
  summary in characters and cuts at a word boundary.
- feedState is nullable instead of a `none` token, and the summary has at
  most five words: "exactly five" made the model pad short views with
  "no data" or "unavailable".
- The HUD caches only the model's words and adds the current warning on
  every paint; an RTL locale gets a leading right-to-left mark.
- The echo check also rejects an all-Latin reply in a non-Latin language,
  translated layer ids and, with every feed healthy, the UNAVAILABLE word;
  places are matched by word and one-word layer names are skipped in
  Latin-script locales.
- The warning tag names the worst layers first; a partial analyst card
  shows one partial chip.

src/testSupport/stubMgrs.mjs

@@ -0,0 +1,22 @@
+// hud.js imports `mgrs`, whose named exports Node's ESM loader cannot read:
+// import this module before hud.js to swap it for a stub.
+import { registerHooks } from 'node:module';
+
+const MGRS_STUB_URL = 'gev-test-stub:mgrs';
+registerHooks({
+  resolve(specifier, context, next) {
+    if (specifier === 'mgrs') return { url: MGRS_STUB_URL, shortCircuit: true };
+    return next(specifier, context);
+  },
+  load(url, context, next) {
+    if (url === MGRS_STUB_URL) {
+      return {
+        format: 'module',
+        shortCircuit: true,
+        source:
+          'export function forward() { return "10SEG55776339"; }\nexport default { forward };\n',
+      };
+    }
+    return next(url, context);
+  },
+});