[glm-grade=B+] feat(i18n): complete card/filter/action translation keys for 31 languages

Full language display names + RTL set (ar/fa/ur) on /i18n/languages;
card.internet/auth/tailscale/dashca, status pills, filter bar and
batch-operation strings added to every language dictionary. Frontend:
English now loads the server dictionary too (keys are semantic ids,
not fallback copy), failed loads keep existing DOM text instead of
exposing raw keys, isLoaded() gate for pre-load renders. Rebuilt
status/dist. Tests: i18n-cards 9/9, full suite 1837/1837.

dashcaddy-api/__tests__/routes/i18n-routes.test.js

@@ -24,13 +24,29 @@ describe('DC-077: i18n Routes', () => {
     expect(res.body.default).toBe('en');
   });
 
-  it('GET /i18n/languages includes RTL flag for Arabic', async () => {
+  it('GET /i18n/languages marks Arabic, Persian, and Urdu as RTL', async () => {
     const app = createI18nApp();
     const res = await request(app).get('/api/v1/i18n/languages');
 
-    const arabic = res.body.languages.find(l => l.code === 'ar');
-    expect(arabic).toBeTruthy();
-    expect(arabic.rtl).toBe(true);
+    const rtl = (code) => {
+      const entry = res.body.languages.find(l => l.code === code);
+      expect(entry).toBeTruthy();
+      expect(entry.name).not.toBe(code);
+      return entry.rtl;
+    };
+    expect(rtl('ar')).toBe(true);
+    expect(rtl('fa')).toBe(true);
+    expect(rtl('ur')).toBe(true);
+    const english = res.body.languages.find(l => l.code === 'en');
+    expect(english.rtl).toBe(false);
+  });
+
+  it('GET /i18n/translations/fa returns Persian strings, not raw English', async () => {
+    const app = createI18nApp();
+    const res = await request(app).get('/api/v1/i18n/translations/fa');
+    expect(res.status).toBe(200);
+    expect(res.body.translations['action.open']).not.toBe('Open');
+    expect(res.body.translations['filter.online']).not.toBe('Online');
   });
 
   it('GET /i18n/translations/en returns English translations', async () => {