feat: distinguish 404 permanent failures from temporary API errors

[Yashaswini-K-P]

Description

Updated scripts/analyze-inactivity.js to distinguish between temporary API errors and permanent account deletions, routing 404 errors into invalid-users.json for manual verification.

Linked Issue

Fixes #353

Changes Made

• Updated fetchData to return { data, status }.
• Implemented logic to read, merge, and alphabetically sort entries in invalid-users.json.
• Separated 404 permanent account failures from temporary network/server failures in the sync loop.

Type of Change

• Bug fix
• New feature
• UI/Visual update
• Documentation update
• Refactor

Testing

• Tested locally
• Tested on mobile viewport (if applicable)
• No console errors introduced

Checklist

• My code follows the project's coding style
• I have formatted my code locally by running npx prettier --write . before submitting
• I am submitting my PR from a dedicated feature/* branch, not the main branch
• I have performed a self-review of my code
• My changes generate no new warnings or errors
• I have updated documentation if required
• I have linked the relevant issue

Screenshots / Screen Recording

N/A (Backend synchronization logic update)

[github-actions]

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[jagdish-15]

I checked the API behavior, and it doesn't return a 404 for an invalid/expired username. It returns 200 OK with an errors array containing "That user does not exist."

Because of this, the current implementation won't detect invalid users correctly. profile will still be truthy, so the 404 branch is skipped and the missing submissionCalendar can cause the user to be incorrectly classified as inactive.