fix(i18n): fix 5 P1/P2 bugs — timeAgo count, community widget, Linux AppImage, locale gaps, lang normalization

- Fix relative-time {{count}} placeholders in all 12 locales (5m ago, not m ago)
- Localize CommunityWidget: replace 3 hardcoded English strings with t() calls
- Add Linux AppImage to tech/finance Tauri configs, CI matrix (ubuntu-22.04), packaging scripts, and download-node.sh
- Fix language code normalization: add supportedLngs/nonExplicitSupportedLngs to i18next, normalize getCurrentLanguage()
- Translate ~240 untranslated English strings across 11 locale files (ru/ar/zh now 100% translated)
- Add components.community section to all 12 locales
- All 12 locales at 1130-key parity, 0 placeholder mismatches

src-tauri/tauri.tech.conf.json

@@ -17,7 +17,8 @@
       "app",
       "dmg",
       "nsis",
-      "msi"
+      "msi",
+      "appimage"
     ],
     "macOS": {
       "hardenedRuntime": true