fix(themes): synchronize github theme accent color between code and docs (JhaSourav07#3174)

## Description
Fixes JhaSourav07#2109 

Synchronized the GitHub theme accent color between implementation and
documentation. The code was using `#39d353` (neon green) while
`THEMES.md` documented `#238636` (GitHub's official brand green),
creating visual inconsistency between what users read in docs and what
got generated.

**Why this matters:**
- Users reading THEMES.md expected to see `#238636`
- Generated badges showed `#39d353` instead
- This caused trust issues and confusion

**Changes made:**
- Updated `lib/svg/themes.ts` — GitHub theme accent: `#39d353` →
`#238636`
- Verified `THEMES.md` aligns with the new color
- Updated available themes count (20 → 24)
- Added unit test in `lib/svg/themes.test.ts` to prevent future
mismatches
- Added integration test in `lib/svg/generator.test.ts`
- All 150 tests passing ✅

## Pillar
- [x] 🎨 Pillar 1 — New Theme Design
- [ ] 📐 Pillar 2 — Geometric SVG Improvement
- [ ] 🕐 Pillar 3 — Timezone Logic Optimization
- [ ] 🛠️ Other (Bug fix, refactoring, docs)

## Visual Preview
GitHub theme badge now displays with `#238636` accent color (brand
green), matching the official documentation.

## Checklist before requesting a review:
- [x] I have read the `CONTRIBUTING.md` file.
- [x] I have tested these changes locally
(`localhost:3000/api/streak?user=YOUR_USERNAME&theme=github`).
- [x] I have run `npm run format` and `npm run lint` locally and
resolved all errors (CI will pass).
- [x] My commits follow the Conventional Commits format (`fix(themes):
...`).
- [x] I have updated `README.md` if I added a new theme or URL
parameter. (Not needed — existing theme updated)
- [x] I have started the repo.
- [x] I have made sure that I have only one commit to merge in this PR.
- [x] The SVG output matches the CommitPulse "premium quality" aesthetic
standard (no raw elements, smooth animations, correct fonts).
- [x] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: JhaSourav07

THEMES.md

@@ -1,6 +1,6 @@
 # CommitPulse Themes
 
-All 20 available themes for your CommitPulse badge. Use the `?theme=<slug>` query parameter to apply a theme.
+All 24 available themes for your CommitPulse badge. Use the `?theme=<slug>` query parameter to apply a theme.
 
 ```
 https://commitpulse.vercel.app/api/streak?user=YOUR_USERNAME&theme=<slug>

lib/svg/generator.test.ts

@@ -242,6 +242,27 @@ describe('generateSVG', () => {
     expect(svg).toContain('ffffff'); // default text
   });
 
+  it('renders correctly with github theme parameters', () => {
+    const svg = generateSVG(
+      mockStats,
+      {
+        user: 'avi',
+        bg: themes.github.bg,
+        text: themes.github.text,
+        accent: themes.github.accent,
+      } as unknown as BadgeParams,
+      mockCalendar
+    );
+
+    assertValidSVG(svg);
+    // Background fill color
+    expect(svg).toContain('#0d1117');
+    // Accent color should be standard brand-consistent #238636
+    expect(svg).toContain('#238636');
+    // Text color should be #ffffff
+    expect(svg).toContain('#ffffff');
+  });
+
   it('adjusts label styling contrast on light backgrounds versus dark backgrounds', () => {
     // 1. Light background (bg: 'ffffff') should use text color for label fill and 0.8 opacity
     const svgLight = generateSVG(

lib/svg/themes.test.ts

@@ -116,6 +116,20 @@ describe('themes', () => {
     });
   });
 
+  describe('github theme', () => {
+    it('asserts github theme exists', () => {
+      expect(themes).toHaveProperty('github');
+      expect(themes.github).toBeDefined();
+    });
+
+    it('asserts github theme has correct color configuration matching the theme specification', () => {
+      expect(themes.github.bg).toBe('0d1117');
+      expect(themes.github.text).toBe('ffffff');
+      expect(themes.github.accent).toBe('238636');
+      expect(themes.github.negative).toBe('f85149');
+    });
+  });
+
   describe('makeTheme produces HexColor branded types', () => {
     const hexRegex = /^[0-9a-f]{6}$/i;
 

lib/svg/themes.ts

@@ -15,7 +15,7 @@ export const themes: Record<string, BadgeTheme> = {
   dark: makeTheme('0d1117', 'c9d1d9', '58a6ff', 'f85149'),
   light: makeTheme('ffffff', '24292f', '0969da', 'cf222e'),
   neon: makeTheme('000000', '00ffcc', 'ff00ff', 'ff0055'),
-  github: makeTheme('0d1117', 'ffffff', '39d353', 'f85149'),
+  github: makeTheme('0d1117', 'ffffff', '238636', 'f85149'),
   dracula: makeTheme('282a36', 'f8f8f2', 'bd93f9', 'ff5555'),
   ocean: makeTheme('0a192f', 'ccd6f6', '64ffda', 'ff6b6b'),
   sunset: makeTheme('1a0a0a', 'ffd6c0', 'ff6b35', 'ff4d4d'),