Added three new projects ("presentation", "core", and
"infrastructure") to the solution file with unique GUIDs.
Updated the `GlobalSection(NestedProjects)` to reflect the
new project structure, nesting the new projects under the
parent project with GUID `{02EA681E-C7D8-13C7-8484-4AC65E1B71E8}`.
Removed outdated nested project mappings and replaced them
with mappings for the new projects. Updated the solution
file to ensure proper integration of the new projects.
