One main rule
A navigable repo answers one question fast: where should I look next? Your teammate, judge, or recruiter should find the UI, API, shared logic, and start command without asking you on WhatsApp.
What reviewers scan
Most reviewers do not read every file. They scan the root folder, package scripts, main app folder, API folder, and README headings.
Your job is not to create a perfect enterprise structure. Your job is to remove confusion from a weekend project.