[FEATURE] Add Dark Mode UI and Bengali (bn) Translations support

[sounak-ghosh03]

I would like to contribute by:

1. Adding a dark mode toggle using Tailwind's dark mode
2. Adding Bengali (bn) translations to improve accessibility for users in West Bengal

I will:

• Follow existing UI patterns
• Keep changes modular
• Ensure no breaking changes

Please let me know if this aligns with the project direction.

[simonlpaige]

Dark mode is straightforward with Tailwind's dark: variant, but there's a consideration for this project: many government data visualizations (charts, maps, tables) rely on color-coded status indicators (e.g., dam levels, crop price trends). You'll need to ensure contrast ratios remain WCAG AA compliant in dark mode for those color-coded elements, not just text/backgrounds.

For Bengali translations, check src/i18n/ — if it uses react-i18next with JSON resource files, adding bn.json and updating the language selector component should be modular. However, note that 10 live districts include West Bengal (Kolkata), so Bengali is relevant, but you'll also want to verify that the translation keys cover all 29 dashboard modules (especially government-specific terms like "Dam Storage Capacity" or "Crop Mandi Price") — those may not have direct Bengali equivalents in official sources.

One potential issue: the README mentions "real-time" data. Some modules (weather, crop prices) update via API polling. Dark mode toggle state should persist across page reloads (localStorage) to avoid flashing white on re-fetch cycles.

[sounak-ghosh03]

Thanks for the detailed feedback.

For dark mode, I'll ensure WCAG AA-compliant contrast not only for text/backgrounds but also for charts, maps, and status indicators. I'll also persist the theme preference via local Storage and prevent theme flashing on reload.

For Bengali localization, I'll review the existing i18n setup, add a modular bn resource file, and audit translation keys across the dashboard modules, using official Bengali terminology where available.

I will keep the changes modular and non-breaking.