This PR resolves a dark mode UI issue where article titles became invisible
on hover due to insufficient contrast.

Changes included:

• Fixed hover styles for article cards in dark mode
• Added a proper dark/light theme toggle in the navbar
• Configured ThemeProvider and Tailwind dark mode support
• Prevented hydration mismatch issues

These changes improve accessibility, consistency, and overall user experience.
Fixes #15

Summary by CodeRabbit

Release Notes

• New Features

  • Added dark mode support with a new theme toggle button for seamless switching between light and dark modes.
  • Redesigned application header with improved responsive layout and enhanced visual styling.

• Style

  • Updated footer border styling for improved visual consistency.
  • Enhanced dark mode compatibility throughout the interface.

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