Update stata do files to use new analysis data and allow for do files to run in isolation from Stata

[NKeleher]

Pull Request Summary 🚀

What does this PR do? 📝

Update the data/raw/sample_data.csv that @krojas01 created in #29 (I fixed the duplicates for ease of running just stata-run but am including a data/raw/sample_data_with_duplicates.csv for use in training and demostrations.

I also made several fixes to the do files in do_files so that each do file can run in isolation either from Stata or using nbstata in VS Code.

Why is this change needed? 🤔

Allow for more elaborate data pipeline demonstrations/training exercises and make it easier for users to work with individual do files from Stata or from VS Code.

How was this implemented? 🛠️

• added the sample_data.csv that Karen created
• added a STANDALONE INITIALIZATION section in each do file that allows each do file to run independently if they don't want to run the do file via do_files/00_run.do

How to test or reproduce? 🧪

• run the full pipeline using just stata-run
• run some of the individual do files independently

Screenshots (if applicable) 📷

Checklist ✅

• I have run and tested my changes locally
• I have limited this PR to less than 1000 lines of code change (if not, explain why)
• I have updated/added tests to cover my changes (if applicable)
• I have updated/added requirements to cover my changes (if applicable)
• I have run linting and formatting on any code changes (if applicable)
• I have updated the documentation (README, etc.) accordingly

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⭐⭐⭐	:star: :star: :star:	Important to fix before PR can be approved... And I am providing reasons why it needs to be addressed as well as suggested improvements.
⭐⭐	:star: :star:	Important to fix but non-blocking for PR approval... And I am providing suggestions where it could be improved either in this PR or later.
⭐	:star:	Give this some thought but non-blocking for PR approval... ...and consider this a suggestion, not a requirement.
❓	:question:	I have a question. This should be a fully formed question with sufficient information and context that requires a response.
📝	:memo:	This is an explanatory note, fun fact, or relevant commentary that does not require any action.
⛏	:pick:	This is a nitpick. This does not require any changes and is often better left unsaid. This may include stylistic, formatting, or organization suggestions and should likely be prevented/enforced by linting if they really matter.
♻️	:recycle:	Suggestion for refactoring. Should include enough context to be actionable and not be considered a nitpick.

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.