fix: resolve backend syntax errors, typing issues, and stabilize analysis tests

[vivekktrivedi06-hue]

Hi @maintainers 👋

This PR fixes multiple backend issues that were causing runtime errors and test failures.

✅ Changes Made

• Fixed invalid characters ("→") causing syntax errors
• Resolved missing typing imports ("List", "Dict")
• Corrected type hints in "line_utils.py"
• Fixed incorrect type usage ("List[Dtr]" → proper typing)
• Cleaned up API response models
• Ensured compatibility with Python 3.11 typing
• Stabilized Playwright E2E test ("analyze.spec.js")

🔍 Result

• ✅ Backend server starts successfully
• ✅ No runtime errors during analysis
• ✅ All tests passing ("1 passed")
• ✅ Improved code stability and maintainability

📌 Notes

• No breaking changes introduced
• Focused on fixing errors and improving reliability

Kindly review and let me know if any changes are needed.

Thank you!

[vivekktrivedi06-hue]

Hi @maintainers 👋

I have resolved multiple backend issues including syntax errors, missing typing imports, and incorrect type hints that were causing runtime failures.

✅ Fixed invalid characters and syntax issues
✅ Added missing "List" and "Dict" imports
✅ Corrected type annotations in "line_utils.py"
✅ Ensured backend runs without errors
✅ Stabilized analysis flow and tests

All tests are now passing successfully ✅

Kindly review the PR. Looking forward to your feedback. 🚀