App theming (3–4 themes)

[mrsumanbiswas]

Introduce a theme switcher with at least 3–4 themes:

• Light (default)
• Dark
• One or two accent‑based themes (e.g., blue, green)

Implementation

• Define theme data in Flutter’s ThemeData
• Persist the user’s choice using SharedPreferences or secure storage
• Add a theme selection screen in settings
• Apply the chosen theme consistently across all screens (text, buttons, app bar, chat bubbles)

Ensure readability and proper contrast in all themes.