feat: add automated code formatting in CI using Black and Prettier

[Shirivarshini]

Description

Added automated code formatting checks to CI using Black and Prettier.

Changes Made:

Added Black formatting checks for backend Python code in ci.yml
Added Prettier formatting checks for frontend files in frontend-checks.yml
Added Prettier configuration (.prettierrc)
Added Prettier as a frontend development dependency
Formatted existing backend and frontend files to comply with the new formatting standards

Related Issue

Fixes #478

Type of change

• Bug fix
• New feature / enhancement
• Documentation update
• Test addition
• Refactor

Checklist

• I have read CONTRIBUTING.md
• My branch is up to date with main
• I have run pytest -v and all tests pass
• I have not introduced duplicate issues or features
• My PR title follows the format: feat/fix/docs/test: short description
• I have added tests for new features (Level 2 and 3 issues)
• No hardcoded secrets or API keys in my code
• This PR is linked to a GSSoC 2026 issue

Screenshots (if frontend change)

N/A (No UI changes. Added CI formatting checks only.)

Test evidence

pytest -v

======================== warnings summary ========================
- StarletteDeprecationWarning
- PydanticDeprecatedSince212

======================== test summary ============================
389 passed, 2 warnings in 3.48s