feat: Add Binary Search Tree (BST) and AVL Tree implementations

[harsha08-2k6]

1. I have read CONTRIBUTING.md
   Read the repository's guidelines and rules for contributors before submitting your PR.

2. This pull request is all my own work -- I have not plagiarized it
   Confirm the code is your own original work, not copied from other sources. Add comments with references if you learned from tutorials.

3. All filenames are in PascalCase
   File names must start with capital letters, no underscores.
   ✅ Correct: BinarySearchTree.java, AVLTree.java, TreeNode.java
   ❌ Wrong: binarySearchTree.java, binary_search_tree.java

4. All functions and variable names follow Java naming conventions

Methods: Use camelCase - insert(), search(), findMin()
Variables: Use camelCase - root, balanceFactor, nodeValue
Classes: Use PascalCase - BinarySearchTree, AVLTree

5. All new algorithms have a URL in their comments that points to Wikipedia
   Add this comment block at the top of each file:
   java/**

• Binary Search Tree Implementation
• Reference: https://en.wikipedia.org/wiki/Binary_search_tree
  */

6. All new code is formatted with clang-format
   Run this command on all your Java files:
   bashclang-format -i --style=file src\main\java\trees*.java
   clang-format -i --style=file src\test\java\trees*.java

[codecov-commenter]

Codecov Report

❌ Patch coverage is 52.70270% with 105 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.24%. Comparing base (fa8ea8e) to head (83fa41f).

Files with missing lines	Patch %	Lines
src/main/java/trees/AVLTree.java	56.14%	39 Missing and 11 partials ⚠️
src/main/java/trees/BinarySearchTree.java	58.75%	30 Missing and 3 partials ⚠️
src/main/java/trees/Main.java	0.00%	22 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7090      +/-   ##
============================================
- Coverage     78.50%   78.24%   -0.26%     
- Complexity     6752     6813      +61     
============================================
  Files           759      763       +4     
  Lines         22402    22624     +222     
  Branches       4400     4424      +24     
============================================
+ Hits          17587    17703     +116     
- Misses         4109     4200      +91     
- Partials        706      721      +15     

☔ 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.