Feat: Added commit diff size trend [ISSUE: #174]

[abdullahxyz85]

Summary [ISSUE: #174 ]

Adds a stacked bar chart showing lines added vs. removed per week over the last 12 weeks, giving insight into codebase growth patterns.

What's Changed

• New DiffTrendChart component in dashboard
• API endpoint to fetch repository code frequency stats
• Aggregates data from top 3 repositories
• Stacked bar chart with lines added (green) and removed (red)
• Handles GitHub 202 response (computing stats state)
• Added CSS color variables for theme consistency

Implementation Details

• Fetches from GitHub API: /repos/{owner}/{repo}/stats/code_frequency
• Displays last 12 weeks of data
• Shows loading, computing, and error states
• Responsive design for all screen sizes
• Full dark mode support

Acceptance Criteria Met: ISSUE: #174

• ✅ New chart widget in dashboard
• ✅ Data from GitHub Stats API
• ✅ Aggregated across top 3 repos
• ✅ Stacked bar with additions/deletions
• ✅ Uses recharts BarChart with two data series
• ✅ Last 12 weeks shown with dates
• ✅ Tooltip shows exact counts
• ✅ Handles 202 response (Computing stats)
• ✅ Uses CSS variables for colors

Visual Overview:

Code Change Trend:

[vercel]

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[abdullahxyz85]

Hi @Priyanshu-byte-coder ,
I completed the issue: #174 , please review and merge it,
and add label: gssoc:approved and level: critical 🙏.

[Priyanshu-byte-coder]

This PR conflicts with recently merged changes. Please rebase onto main:

git fetch upstream && git rebase upstream/main

Resolve any conflicts, push, and I'll review.

[Priyanshu-byte-coder]

Hi @abdullahxyz85 — this PR has a merge conflict with main. Please rebase your branch:

git fetch upstream
git rebase upstream/main
# resolve conflicts, then:
git push --force-with-lease

Once rebased, we'll review and merge.

[abdullahxyz85]

Sure, i am doing!

[abdullahxyz85]

@Priyanshu-byte-coder I resolved the conflicts , please review and add label: gssoc:approved and level.

[abdullahxyz85]

Closing to reopen as separate, isolated feature PRs for proper review

[Priyanshu-byte-coder]

Same bundling problem as #321 — please clean up before merge:

1. Remove already-merged files after rebasing
The following files are already in main (merged via #336 and earlier PRs). After rebasing, delete them from this branch:

• src/app/api/leaderboard/route.ts
• supabase/migrations/20260519000000_add_leaderboard_opt_in.sql
• src/app/leaderboard/page.tsx

2. Scope this PR to DiffTrendChart only
This PR touches prs/route.ts, issues/route.ts, settings/page.tsx, BadgeSection.tsx, TopRepos.tsx, supabase.ts, tsconfig.json — none of these are related to the diff size trend feature. Revert any changes not specifically needed for DiffTrendChart.

The files that belong in this PR:

• src/components/DiffTrendChart.tsx ✓
• src/app/api/metrics/diff-trend/route.ts ✓
• src/app/globals.css (adding --success / --destructive tokens) ✓
• src/app/dashboard/page.tsx (registering the widget) ✓
• e2e/dashboard-widgets.spec.js (mocking the new route) ✓

The chart component itself looks good: CSS vars throughout, proper loading/error/computing/empty states, clean recharts usage. Just needs the cleanup above.

[abdullahxyz85]

I closed these PR's and opened new PR

Same bundling problem as #321 — please clean up before merge:

1. Remove already-merged files after rebasing The following files are already in main (merged via #336 and earlier PRs). After rebasing, delete them from this branch:

• src/app/api/leaderboard/route.ts
• supabase/migrations/20260519000000_add_leaderboard_opt_in.sql
• src/app/leaderboard/page.tsx

2. Scope this PR to DiffTrendChart only This PR touches prs/route.ts, issues/route.ts, settings/page.tsx, BadgeSection.tsx, TopRepos.tsx, supabase.ts, tsconfig.json — none of these are related to the diff size trend feature. Revert any changes not specifically needed for DiffTrendChart.

The files that belong in this PR:

• src/components/DiffTrendChart.tsx ✓
• src/app/api/metrics/diff-trend/route.ts ✓
• src/app/globals.css (adding --success / --destructive tokens) ✓
• src/app/dashboard/page.tsx (registering the widget) ✓
• e2e/dashboard-widgets.spec.js (mocking the new route) ✓

The chart component itself looks good: CSS vars throughout, proper loading/error/computing/empty states, clean recharts usage. Just needs the cleanup above.

I closed these PR's and opened new PR