Implement a file-naming convention that is safe

Currently on ``ehr-utils.js``, we have a function called ``makeSafeFileName`` which needs to be implemented in a way that doesn't break the build.

Previously (as you can see it commented out currently), we used to implement [``filenamify``](https://www.npmjs.com/package/filenamify) to handle this, but this implementation was breaking the build.

With that in mind, the task at hand is to create a new implementation (or re-implement filenamify) in a way that won't break the build. We encorage using conventions that are easy to read and understand at first glance.

Start in ehr-utils.js by reading makeSafeFileName and the commented-out filenamify usage, then run the project build to reproduce the reported failure. Define the supported safe-naming behavior from the existing context and confirm that the implementation preserves the build while producing readable file names.

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