add Elementary Cellular Automaton (Rule 30) implementation (Hacktoberfest 2025)

[Craniace]

Elementary Cellular Automaton (Rule 30) implementation

Describe your change:

• Add an algorithm
• Fix a bug or typo in an existing algorithm
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, I have opened a single PR for this algorithm.
• All new Python files are placed inside an existing directory (e.g., cellular_automata/).
• All filenames are in all lowercase characters with no spaces or dashes.
• All function and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".

[cclauss]

Nice!

• #15081 (comment)