Implemented FFT convolution and lazy segment tree — fast and efficient

[jsjgdh]

Added implementation of FFT (Cooley–Tukey) for polynomial convolution.
Also added a segment tree with lazy propagation for range updates and queries.
I have included test for both and also tested it locally on my machine .

[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.16514% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.11%. Comparing base (08d8c6b) to head (a1f9075).

Files with missing lines	Patch %	Lines
Maths/FFT.js	97.36%	4 Missing ⚠️
Trees/SegmentTree.js	97.26%	2 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@ ## master #1848 +/- ## ========================================== + Coverage 85.91% 86.11% +0.19%  ========================================== Files 379 382 +3 Lines 19778 20105 +327 Branches 3015 3085 +70 ========================================== + Hits 16993 17314 +321  - Misses 2785 2791 +6 

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.