rebrand: Workavia Calendar

User-facing strings:
- "Twake Calendar" -> "Workavia Calendar" in 4 locales (en/fr/ru/vi)
- public/index.html <title>
- public/manifest.appdata (name + short_name)
- VALARM description string (sent to participants in iCal)

Defaults / neutralization:
- Video conference fallback URL: meet.linagora.com -> meet.jit.si
  (still overridable via window.VIDEO_CONFERENCE_BASE_URL or .env.js)

Kept intact (design system / non user-facing):
- @linagora/twake-mui package + TwakeMuiThemeProvider class
  (primary colors preserved per requirement)
- public/calendar.svg, app-*.svg icons (no embedded text)

public/index.html

@@ -18,7 +18,7 @@
     -->
     <link rel="stylesheet" href="<%= assetPrefix %>/fonts/fonts.css" />
 
-    <title>Twake Calendar</title>
+    <title>Workavia Calendar</title>
     <script src="<%= assetPrefix %>/.env.js"></script>
     <script src="<%= assetPrefix %>/appList.js"></script>
   </head>