feat: add toast notifications for analytics data fetching errors

[shankumar7]

Summary

This PR addresses unhandled promise rejections and silent failures across several components by ensuring all .catch() blocks properly log errors to the console and surface user-facing toast notifications.

Closes #1350

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup

Changes Made

• CommitTimeChart.tsx: Added toast.error and console.error to fetchContributions.
• RepoAnalyticsExplorer.tsx: Added toast.error and console.error to fetchRepos.
• StreakTracker.tsx: Added console.error to fetchStreak, fetchFreeze, handleApplyFreeze, handleCancelFreeze, and handleCopy.
• CommunityMetrics.tsx: Added toast.error and console.error to fetchMetrics.
• settings/page.tsx: Added toast.error to handleTogglePublic, handleToggleLeaderboard, handleRemoveAccount, and console.error to copyShareLink.

How to Test

Steps for the reviewer to verify this works:

1. Log into the Dashboard.
2. Open your browser's Developer Tools and go to the Network tab.
3. Block the request URL for any of the affected APIs (e.g., contributions, streak, discussions, repo-explorer).
4. Refresh the page and verify that a red toast notification appears and the error is logged in the Console.

Screenshots (if UI change)

N/A - Only adds toast notifications on error.

Checklist

• Linked issue in summary
• npm run lint passes locally
• No TypeScript errors (npm run type-check)
• Self-reviewed the diff
• Added/updated tests if applicable

[vercel]

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

[shankumar7]

@Priyanshu-byte-coder please add gssoc:approved label