feat: Add Iris Dataset Explorer Example

[Codexnever]

This pull request adds a new example to the project: the Iris Dataset Explorer. This example demonstrates how to build an interactive data explorer using Preswald with the classic Iris dataset. The example includes:

• hello.py: The main script that loads the Iris dataset (from multiple potential sources), displays an overview with statistics, and renders interactive visualizations (scatter plots for sepal and petal dimensions) using Plotly.
• data/iris.csv: The Iris dataset in CSV format (used if available; otherwise, sample data is generated).
• README.md: Documentation outlining how to run the example and explaining its features.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• New example
• Test improvement

Testing

• Ran the example locally using:

  preswald run hello.py

  (or, if not in PATH:

  C:\Users\user\AppData\Roaming\Python\Python313\Scripts\preswald.exe run hello.py

  )
• Verified that the Iris dataset loads correctly (via multiple fallback options) and that the interactive visualizations (scatter plots) display as expected.
• Checked that the README provides clear instructions and that the file structure is correct.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have run my code against examples and ensured no errors
• Any dependent changes have been merged and published in downstream modules