Add translations to the landing page to support multiple languages

Adds i18n support to LandingPage.tsx and introduces new keys in en.json and ar.json for translating landing page content.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 5a4f78b4-6a2e-4391-b005-5544e086dac8
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/9777c70b-fc38-4831-8d6b-78dfffe041b0/b281d9b5-65f2-4854-b74e-21841ec0541a.jpg

client/src/i18n/locales/en.json

@@ -315,6 +315,14 @@
     "invalidCredentials": "Invalid credentials",
     "passwordMismatch": "Passwords do not match"
   },
+  "landing": {
+    "heroTitle": "Voice-Powered",
+    "heroSubtitle": "Complete offline task and financial management with local AI voice processing. No internet required, complete privacy guaranteed.",
+    "taskManagement": "Task Management",
+    "taskManagementDesc": "Voice-powered task creation",
+    "financialTracking": "Financial Tracking", 
+    "financialTrackingDesc": "Automated expense logging"
+  },
   "dashboard": {
     "title": "Dashboard",
     "welcome": "Welcome",