feat: add Vision Transformer (ViT) implementation for image classification (#13334)

* docs: enhance README with table of contents, installation guide, and features section

- Add comprehensive table of contents for easy navigation
- Include detailed installation steps with virtual environment setup
- Add usage examples showing how to run and import algorithms
- Create features section listing all algorithm categories
- Add explicit license section with MIT License information
- Expand contributing section with quick start guide
- Add about section explaining repository purpose

Fixes #13111

* docs: enhance README with table of contents, installation guide, and features section

- Add comprehensive table of contents for easy navigation
- Include detailed installation steps with virtual environment setup
- Add usage examples showing how to run and import algorithms
- Create features section listing all algorithm categories
- Add explicit license section with MIT License information
- Expand contributing section with quick start guide
- Add about section explaining repository purpose

Fixes #13111

* feat: add Vision Transformer (ViT) implementation for image classification

- Implement complete ViT architecture with patch embedding
- Add positional encoding with learnable CLS token
- Include scaled dot-product attention mechanism
- Implement transformer encoder blocks with layer normalization
- Add feed-forward network with GELU activation
- Include comprehensive docstrings and type hints
- Add doctests for all functions
- Provide example usage demonstrating the complete pipeline

Fixes #13326

* fix: resolve ruff linting errors in vision_transformer.py

- Replace Optional with X | None syntax (UP045)
- Use np.random.Generator instead of legacy np.random methods (NPY002)
- Fix line length violations (E501)
- Assign f-string literals to variables in exceptions (EM102)
- Remove unused variables and parameters (RUF059, F841)
- Add noqa comment for intentionally unused API parameter
- All doctests still pass successfully

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* refactor: use descriptive parameter names instead of 'x'

- Rename 'x' to 'embeddings' in layer_norm, feedforward_network,
  and transformer_encoder_block functions
- Update all docstring examples to use 'embeddings'
- Improves code readability per algorithms-keeper bot feedback
- Fix noqa comment placement for unused num_heads parameter
- All doctests and ruff checks pass

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* updating DIRECTORY.md

* Remove redundant sections from README.md

Removed sections on Table of Contents, About, Features, and Contributing from README.

---------

Co-authored-by: devvratpathak <devvrat.23bce8848@vitapstudent.ac.in>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>
Co-authored-by: pre-commit-ci[bot] <pre-commit-ci[bot]@users.noreply.github.com>

Author: 4 people

DIRECTORY.md

@@ -188,6 +188,7 @@
   * [Mean Threshold](computer_vision/mean_threshold.py)
   * [Mosaic Augmentation](computer_vision/mosaic_augmentation.py)
   * [Pooling Functions](computer_vision/pooling_functions.py)
+  * [Vision Transformer](computer_vision/vision_transformer.py)
 
 ## [Conversions](conversions)
   * [Astronomical Length Scale Conversion](conversions/astronomical_length_scale_conversion.py)