refactor: the thesaurus is called Synonyms in the UI

Both products name the tool after what it is, which says nothing to a
reader who does not know the word. Every label is "Synonyms" now — ribbon,
context menu, tools menu, dialog — and "thesaurus" stays in the tooltip so
it is still findable by name. Keys and code keep the technical name.

src/App.svelte

@@ -1282,7 +1282,7 @@
             <button class="theme-option" onclick={() => { themeOpen = false; autoTextOpen = true; }} role="menuitem">
               <span>{t().autoText.title}</span>
             </button>
-            <button class="theme-option" onclick={() => { themeOpen = false; thesaurusOpen = true; }} role="menuitem">
+            <button class="theme-option" onclick={() => { themeOpen = false; thesaurusOpen = true; }} role="menuitem" title={t().thesaurus.hint}>
               <span>{t().thesaurus.title}</span>
               <span class="theme-option-hint">{shortcutHint('thesaurus')}</span>
             </button>

src/lib/components/CLAUDE.md

@@ -151,13 +151,18 @@ Text group, the classic chrome's Tools menu): the library, a click to insert, an
 from selection" — the selected slice serialized to HTML. `hasSelection` is derived off
 `open` because the dialog stays mounted and a modal freezes the selection it opened on.
 
-## Thesaurus (`ThesaurusDialog.svelte`, `spell/thesaurus.ts`)
+## Synonyms (`ThesaurusDialog.svelte`, `spell/thesaurus.ts`)
 
 LibreOffice's Tools ▸ Thesaurus (Ctrl+F7), reachable where Word puts it too (the ribbon's
 Review ▸ Proofing) and from the context menu: the word at the caret (`wordRangeAt`), the
 groups it appears in, click one to replace it. The box above looks up any other word,
 which is how both dialogs follow a chain.
 
+**Named "Synonyms", not "Thesaurus"** — the one place the label deviates from both
+products. The word of art names the tool without saying what it does; it stays in the
+tooltip (`thesaurus.hint`) so anyone looking for it still finds it. The i18n keys and
+the code keep the technical name.
+
 - The data is `public/thesaurus/<code>/<code>.txt`, one `;`-separated group per line,
   generated from LibreOffice's own MyThes files by `scripts/make-thesaurus.mjs` — de 3.0MB
   / 37k groups, en 6.7MB / 143k groups. MyThes repeats every group once per member, ten

src/lib/components/ribbon/tabs/ReviewTab.svelte

@@ -53,7 +53,7 @@
     variant="big"
     icon="thesaurus"
     label={t().thesaurus.title}
-    title={`${t().thesaurus.title} (${shortcutHint('thesaurus')})`}
+    title={`${t().thesaurus.hint} — ${shortcutHint('thesaurus')}`}
     onclick={() => window.dispatchEvent(new CustomEvent(OPEN_THESAURUS_EVENT))}
   />
   <div class="rb-menu-wrap" use:clickOutside={'wordCount'}>

src/lib/i18n/locales/de.ts

@@ -485,10 +485,13 @@ const de: Messages = {
     ignoreAll: 'Alle ignorieren',
   },
   thesaurus: {
-    title: 'Thesaurus',
-    menuItem: 'Thesaurus…',
+    // "Thesaurus" heißt das Werkzeug in beiden Programmen, sagt aber nicht, was es tut:
+    // sichtbar ist überall "Synonyme", der Fachbegriff steht im Tooltip.
+    title: 'Synonyme',
+    menuItem: 'Synonyme…',
+    hint: 'Ein anderes Wort mit gleicher Bedeutung finden (Thesaurus)',
     lookUp: 'Nachschlagen',
-    word: 'Wort',
+    word: 'Wort eingeben…',
     loading: 'Wird geladen…',
     replaceHint: 'Ein Wort anklicken, um es im Dokument zu ersetzen.',
     noSynonyms: 'Keine Synonyme gefunden',

src/lib/i18n/locales/en.ts

@@ -489,10 +489,13 @@ const en = {
     ignoreAll: 'Ignore All',
   },
   thesaurus: {
-    title: 'Thesaurus',
-    menuItem: 'Thesaurus…',
+    // Both products call the tool "Thesaurus", which does not say what it does: the
+    // label everywhere is "Synonyms", the term of art lives in the tooltip.
+    title: 'Synonyms',
+    menuItem: 'Synonyms…',
+    hint: 'Find another word with the same meaning (thesaurus)',
     lookUp: 'Look up',
-    word: 'Word',
+    word: 'Enter a word…',
     loading: 'Loading…',
     replaceHint: 'Click a word to replace the one in the document.',
     noSynonyms: 'No synonyms found',