Cleanups + a bunch of new features based on production usage

[sn]

This pull request introduces a significant update to YDNATL, focusing on expanding HTML tag support, enhancing documentation, improving developer tooling, and adding new features for building HTML UIs in Python. The changes make the library more versatile and developer-friendly, especially for use cases involving UI serialization, drag-and-drop builders, and readable HTML generation.

Documentation and Feature Additions

• Expanded the README.md to document new features: JSON serialization/deserialization, pretty printing, CSS style helpers, method chaining, context manager support, and fragment support for wrapper-free grouping. Also added detailed usage examples and clarified element/class method lists. [1] [2] [3]
• Updated the documentation to list all newly supported HTML5 tags and components, reflecting the expanded API surface. [1] [2] [3] [4] [5]

API and Tag Support

• Added imports and __all__ exports for many new HTML elements (e.g., Fragment, Legend, Output, Progress, Meter, Base, Noscript, Article, Aside, Details, Summary, Dialog, Track, Embed, Object, Param, Map, Area, Caption, Col, Colgroup, Bold, Del, Ins, Strikethrough, Underline, Kbd, Samp, Var, Mark, Dfn, Br, Wbr) in src/ydnatl/__init__.py. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]

Developer Experience and Tooling

• Updated pyproject.toml to version 1.0.6, improved the project description, and added black and flake8 for code formatting and linting in the development dependencies. [1] [2]
• Removed the legacy run_tests.py script in favor of standard pytest usage, streamlining testing instructions and tooling. [1] [2]

Core Improvements

• Refactored src/ydnatl/core/element.py to clean up imports, add type hints, and prepare for new features such as JSON serialization.

Minor Fixes and Text Improvements

• Fixed typos and improved phrasing in documentation for clarity and professionalism.

These changes collectively make YDNATL more robust, easier to use, and ready for advanced UI-building scenarios.