feat(i18n): localize plugin catalog names and shell preset desc

Catalog entry names (15 tab + 4 viewer) and the dsh-desktop shell preset
desc were raw hardcoded zh strings rendered straight into the add-plugin
modals and the title-bar scheme dropdown. Mirror the existing desc
pattern exactly: PluginEntry.name / ShellPreset.desc widen to the
i18n-friendly string-or-() =>-string union, the catalogs carry lazy
t('pluginXxxName') / t('presetDshDesktopDesc') lookups, and the
add-plugin modal (render, search filter, aria-labels) plus the scheme
SelectMenu resolve them like every other copy. The plain-string arm of
the union stays as the raw-name fallback, and t() itself never yields
empty text (missing keys render the key), so a dict gap can never blank
a name.

20 new dictionary keys added to zh/en (locales.ts), ja (locales-ja.ts),
and all 18 third-language dictionaries — tests/locales.spec.ts enforces
key-set equality against zh for every shipped dict (precedent: 9cc642b),
so the 'leave other locales-* untouched' shortcut would fail the hard
parity gate; real translations are provided instead.

Spec follow-ups (behavior change: names/descs now render through t()):
- plugin-list.spec.ts: name non-empty assertion resolves the union.
- add-plugin-modal.spec.tsx: sentinel/office name assertions resolve
  from the catalog (en locale in tests) instead of pinning zh literals.
- shell-presets.spec.ts: desc non-empty assertion resolves the union.

src/client/add-plugin-modal.tsx

@@ -56,8 +56,9 @@ export function PluginListBody(props: { service: BetterSidebarService; kind: Plu
   const needle = query.trim().toLowerCase()
   const matches = (entry: PluginEntry): boolean => {
     if (needle === '') return true
+    const name = typeof entry.name === 'function' ? entry.name() : entry.name
     const description = typeof entry.description === 'function' ? entry.description() : entry.description
-    return entry.name.toLowerCase().includes(needle)
+    return name.toLowerCase().includes(needle)
       || entry.id.toLowerCase().includes(needle)
       || description.toLowerCase().includes(needle)
   }
@@ -93,8 +94,12 @@ export function PluginListBody(props: { service: BetterSidebarService; kind: Plu
     window.open(entry.url, '_blank', 'noopener')
   }
 
-  /** One catalog row (extracted so the group render stays flat). */
-  const renderEntry = (entry: PluginEntry): ReactNode => (
+  /** One catalog row (extracted so the group render stays flat). The name
+   *  resolves like the description (string or () => string) so it follows
+   *  the active locale; a plain-string entry keeps its raw name. */
+  const renderEntry = (entry: PluginEntry): ReactNode => {
+    const name = typeof entry.name === 'function' ? entry.name() : entry.name
+    return (
     <div key={entry.id} className={css.pluginEntry}>
       <div className={css.pluginEntryHead}>
         {/* The name is a BUTTON on the same window.open path as the
@@ -104,16 +109,16 @@ export function PluginListBody(props: { service: BetterSidebarService; kind: Plu
         <button
           type="button"
           className={css.pluginName}
-          aria-label={`${t('openPlugin')}: ${entry.name}`}
+          aria-label={`${t('openPlugin')}: ${name}`}
           onClick={() => { jump(entry) }}
         >
-          {entry.name}
+          {name}
         </button>
         <span className={css.pluginEntryActions}>
           <button
             type="button"
             className={css.pluginJumpBtn}
-            aria-label={`${t('openPlugin')}: ${entry.name}`}
+            aria-label={`${t('openPlugin')}: ${name}`}
             onClick={() => { jump(entry) }}
           >
             {t('openPlugin')}
@@ -121,7 +126,7 @@ export function PluginListBody(props: { service: BetterSidebarService; kind: Plu
           <button
             type="button"
             className={css.pluginCopyBtn}
-            aria-label={`${t('copyInstall')}: ${entry.name}`}
+            aria-label={`${t('copyInstall')}: ${name}`}
             onClick={() => { copy(entry) }}
           >
             {copiedId === entry.id ? t('copied') : t('copy')}
@@ -133,7 +138,8 @@ export function PluginListBody(props: { service: BetterSidebarService; kind: Plu
       </div>
       <code className={css.pluginInstall}>{entry.install}</code>
     </div>
-  )
+    )
+  }
 
   return (
     <div className={css.pluginList}>