fix: resolve low contrast input text in light mode(#290)(#291)

[AkhileshPachnanda]

Description

Please include a summary of the changes and the rationale behind them. Reference any files, components, or modules modified.

Fixes #290 & #291

Description

This PR resolves a contrast issue in Light Mode where user-entered text in input fields (such as on the Sign Up and Sign In pages) was hardcoded to white (text-white), resulting in low contrast (white text on a light gray background).

Rationale & Changes:
Instead of modifying text-white classes on dozens of individual component inputs across the codebase, a clean, global CSS override was added to src/index.css targeting all input, textarea, and select elements when Light Mode is active (html:not(.dark)). This safely forces entered text to use the theme-aware var(--text-primary) color (black/dark gray) in Light Mode, while keeping it white in Dark Mode.

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings or console errors
• I have run tests locally (pnpm run test or vitest run under backend/) and they pass
• Any dependent changes have been merged and published in downstream modules

Verification Details

1. Manual Verification

Steps to reproduce:

1. Run the frontend application and toggle Light Mode.
2. Navigate to the Sign Up (/signup) or Sign In (/signin) page.
3. Type text into the input fields (Name, Email, Password, etc.).
4. Toggle back to Dark Mode and type inside the fields.

Expected result:

• In Light Mode: The entered text is fully visible in dark gray/black (#0f172a), providing high contrast against the input field background.
• In Dark Mode: The entered text remains white (#f9fafb) as before.

Visual Documentation