…ith tests

- Moved TreeMapNode class to the Tree directory for better structure.
- Created TreeNode.php with full implementation.
- Added comprehensive tests for TreeNode, covering left and right child handling, parent removal, and node replacement.
- Ensured 100% test coverage for TreeNode functionality.

refactor(Tree): Move TreeMapNode to Tree directory and add TreeNode w…

This commit enhances both ArrayList and LinkedList classes to provide
better key handling, consistent exception throwing, and support for
mixed key types. It improves type safety, performance, and API consistency.

ArrayList changes:
- Add isValidArrayKey method for key validation (int or string)
- Update set method to throw exceptions for invalid keys and out-of-range indices
- Modify hasKey method to use isValidArrayKey and array_key_exists
- Update get method to use the new hasKey implementation
- Add keyToString method for better error messages
- Simplify contains method using in_array for better performance

LinkedList changes:
- Modify set and get methods to support mixed key types
- Implement findNode method to locate nodes by index or value
- Add compareValues method for flexible element comparison
- Update exception messages to include key information
- Ensure consistent behavior between numeric and non-numeric keys

General:
- Update method signatures to use mixed type consistently across both classes
- Improve code comments and method descriptions

refactor(Collections): improve ArrayList and LinkedList implementations

fix: remove check hasKey in set method

This commit addresses a series of issues identified by PHPStan, enhancing the overall type safety and robustness of the data structures.

- **BinaryHeap:** Corrected type inference by specifying the heap property as a `list`, which eliminates the need for explicit integer casting when removing elements.
- **TreeMap/TreeMapNode:** Fixed a potential null pointer exception in `balanceAfterInsertion` by adding a safety check for the grandparent node.
- **HashMap:** Refactored to use a consistent internal key handling mechanism, resolving type errors and adding proper support for object keys.
- **ArrayList:** Fixed a `Cannot cast mixed to string` error by explicitly handling the `resource` type.
- **phpstan.neon:** Cleaned up the configuration by removing obsolete ignored error patterns.

fix(style-code): Resolve static analysis errors and improve type safety