fix(hi): replace Latin transliteration with Devanagari script in messages.json

[nitinvishway]

🇮🇳 Fix: Hindi locale translations corrected to Devanagari script

Summary

This PR corrects the Hindi translations in messages.json. The existing strings were written in Latin transliteration (romanized Hindi) rather than Devanagari, which is the standard and expected script for the hi locale.

This is a correctness fix — not a content change. The meaning of the strings is preserved; only the script has been updated to what Hindi speakers actually read and expect.

Root Cause

The original translations appear to have been added using phonetic/transliterated text (e.g. "Model jodein") instead of proper Unicode Devanagari (e.g. "मॉडल जोड़ें"). This likely happened during initial string authoring without a native Hindi reviewer.

Changes Made

• File: messages.json
• Scope: All hi locale message strings that used Latin script
• Type: Translation correction (script change only, no structural changes)

Before / After Example

// Before
"addModel": {
  "message": "+ Model jodein"
}

// After
"addModel": {
  "message": "मॉडल जोड़ें"
}

Checklist

• All affected strings updated to Devanagari
• Message keys and JSON structure unchanged
• No other locales modified