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/locales-id.ts

@@ -419,4 +419,24 @@ export const id: Record<string, string> = {
   pluginDocsPanelDesc: 'Dokumen global di sidebar DSH: baca catatan Markdown Anda sendiri dari ruang kerja apa pun — daftar berkas, kerangka, buka di Chrome / VS Code, dan tombol salin; direktori docs dapat dikonfigurasi (default ~/.dsh/docs)',
   pluginEgoBrowserDesc: 'Browser agen untuk DeepSeek Harness: 32 alat ego_* menggerakkan Chromium sungguhan; tab «ego browser» native di bilah samping menampilkan langsung setiap halaman yang dikunjungi agen — Anda bisa mengklik, menyeret, dan mengetik untuk mengambil alih. Tab terdaftar otomatis jika better-sidebar terpasang; jika tidak, jatuh ke gelembung mengambang',
   pluginBilingualReaderDesc: 'Baca PDF di sidebar DSH: tampilan PDF asli, pilih teks untuk diterjemahkan dengan LLM, dengan konteks dan sepenuhnya terisolasi dari percakapan utama',
+  pluginSentinelName: 'dsh-sentinel Sistem bangun',
+  pluginEgoBrowserName: 'ego-browser Peramban agen',
+  pluginBetterOverleafName: 'dsh-better-overleaf Tab Overleaf',
+  pluginDocsPanelName: 'dsh-docs-panel Dokumen global',
+  pluginFlowglassName: 'dsh-flowglass Flowglass',
+  pluginGitForgeName: 'dsh-git-forge Kredensial Git',
+  pluginGitRemotesName: 'dsh-git-remotes Remote Git',
+  pluginGithubWorkbenchName: 'dsh-github-workbench Meja kerja GitHub',
+  pluginSidebarQaName: 'dsh-sidebar-qa Pilih & tanya',
+  pluginSidenoteName: 'dsh-sidenote Obrolan samping',
+  pluginServerDeckName: 'dsh-server-deck Dek server',
+  pluginSuhuangScrollName: 'dsh-suhuang-scroll Suhuang Scroll',
+  pluginSshTunnelName: 'dsh-ssh-tunnel Terowongan SSH',
+  pluginTurnReviewName: 'dsh-turn-review Tinjauan giliran',
+  pluginBilingualReaderName: 'dsh-bilingual-reader Pembaca dwibahasa',
+  pluginOfficeName: 'Pratinjau Office',
+  pluginMdExportName: 'Ekspor Markdown',
+  pluginCodeNavName: 'Navigator pratinjau kode',
+  pluginVideoPreviewName: 'Pratinjau video',
+  presetDshDesktopDesc: 'Mode Electron lanjutan (tanpa bingkai): macOS mencadangkan 20px di atas; Windows mencadangkan 32px untuk bilah judul saat WCO tidak tersedia',
 }