Process reads all files from the specified directory within the embedded filesystem,
executes them as text/templates with the provided data, and writes the results
to the destination directory, preserving the directory structure.
Files named POST_QUICKSTART.md are skipped and not copied to the destination.
ProcessPostQuickstart reads and processes the POST_QUICKSTART.md file from the template directory.
Returns the processed content as a string, or empty string if the file doesn't exist.