feat: Hindi + Tamil + Telugu + Bengali + Kannada + Malayalam localization

[ajithakdev]

Summary

Add native Indian language support to serve India's 900M+ internet users, most of whom prefer their regional language.

Priority Indian languages

Language	Speakers	Code
🇮🇳 Hindi	600M+	hi
🇮🇳 Tamil	80M+	ta
🇮🇳 Telugu	85M+	te
🇮🇳 Bengali	100M+	bn
🇮🇳 Kannada	50M+	kn
🇮🇳 Malayalam	38M+	ml
🇮🇳 Marathi	95M+	mr
🇮🇳 Gujarati	55M+	gu

Key strings to translate

• Button labels: "Start Test", "Cancel", "History", "Export"
• Quality labels: "Excellent", "Good", "Fair", "Poor"
• Use-case labels: "Calls", "Streaming", "Gaming", "Uploads"
• Status messages: "Downloading...", "Uploading...", "Test complete"
• Human-readable explanations: "Good for video calls", "May experience buffering"
• Settings page text
• Error messages

Why India-first

• Largest internet user base globally
• Most Chrome users worldwide are in India
• Very few browser extensions offer Indian language support
• Chrome Web Store algorithm boosts localized extensions in regional searches
• BSNL/Jio/Airtel users specifically searching for speed test tools in their language

Implementation

• Build on the i18n foundation (issue feat: Internationalization (i18n) — multi-language support via chrome.i18n #14)
• Use chrome.i18n API with _locales/hi/messages.json, etc.
• Chrome auto-detects browser language and loads correct locale
• Contribute via community (open for translation PRs)