fix(notification-bell): improve error handling for notification requests

[joshnajojo12]

Closes #1659

Summary

This PR improves error handling in the NotificationBell component by preventing notification-related API failures from being silently ignored.

Changes Made

• Added dedicated error handling for notification fetch failures.
• Added user-friendly feedback when notifications cannot be loaded.
• Improved handling of mark-as-read request failures.
• Removed silent failure paths that made debugging difficult.
• Preserved existing notification functionality and user experience.

Testing

• npm run lint ✅
• npm run type-check ✅

Files Changed

• src/components/NotificationBell.tsx

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[github-actions]

GSSoC Label Checklist 🏷️

@Priyanshu-byte-coder — please apply the appropriate labels before merging:

Difficulty (pick one):

• level:beginner — 20 pts
• level:intermediate — 35 pts
• level:advanced — 55 pts
• level:critical — 80 pts

Quality (optional):

• quality:clean — ×1.2 multiplier
• quality:exceptional — ×1.5 multiplier

Validation (required to score):

• gssoc:approved — counts for points
• gssoc:invalid / gssoc:spam / gssoc:ai-slop — does not score

Type labels (type:*) are auto-detected from files and title. Review and adjust if needed.
Points formula: (difficulty × quality_multiplier) + type_bonus

[joshnajojo12]

Closing this PR because the changes are already present in the base branch.