Phase 9: ESL superpowers — Chinese gloss + tone-rewrite

Inline Chinese gloss (offline) and a "say it more naturally" / tone-rewrite,
the two ESL features for the Mandarin-speaking writer.

Gloss: embedded English→Chinese dictionary (gloss.json.gz, 57k common words
built from ECDICT via scripts/build_gloss.py). lexicon gains Gloss()/Result.Gloss
and a lightweight GET /api/gloss/{word}; the right-click WordCard leads with the
中文; GlossTip shows it on a 350ms hover (reuses wordAt, so CJK is never glossed).
Offline + instant, works with the LLM down.

Rewrite: selecting text pops a SelectionBubble (✨更自然 + the tone vocabulary);
picking a style calls POST /api/docs/:id/rewrite (llm.RunRewrite, stateless,
owner-scoped) and shows a RewritePreview (original→rewrite, accept/cancel/retry).
Accept applies it in-editor.

Tests added in lexicon and suggestions. go build/vet/test, tsc, vite all clean;
live smoke vs a fake vLLM verified gloss + rewrite + 400/404/502 paths.

Claude-Session: https://claude.ai/code/session_016Yr6jELuRc7hyzYLccQKZd

web/src/components/Editor/WordCard.tsx

@@ -17,7 +17,8 @@ interface Props {
 export function WordCard({ word, info, loading, style, onReplace }: Props) {
   const definitions = info?.definitions ?? []
   const synonyms = info?.synonyms ?? []
-  const empty = !loading && definitions.length === 0 && synonyms.length === 0
+  const gloss = info?.gloss ?? ''
+  const empty = !loading && !gloss && definitions.length === 0 && synonyms.length === 0
 
   return (
     <div
@@ -47,6 +48,19 @@ export function WordCard({ word, info, loading, style, onReplace }: Props) {
         </span>
       </div>
 
+      {/* Chinese gloss first — it's what the Mandarin-speaking writer reaches for. */}
+      {gloss && (
+        <p
+          className="mt-2.5 leading-snug"
+          style={{
+            color: 'var(--color-plum)',
+            fontFamily: "'Nunito','PingFang SC','Microsoft YaHei','Noto Sans CJK SC',sans-serif",
+          }}
+        >
+          {gloss}
+        </p>
+      )}
+
       {loading && (
         <div className="mt-3 inline-flex items-center gap-1.5" style={{ color: 'var(--color-muted)' }}>
           <span