Fix test: use README.md (uppercase) for case-sensitive filesystems

- Changed readme.md to README.md in sampleFiles.spec.ts
- Fixes test failures on Linux/Ubuntu (case-sensitive filesystem)
- macOS is case-insensitive so it worked, but Linux requires exact case
- All 17 tests now pass on all platforms

Author: Nolin Naidoo

src/sampleFiles.spec.ts

@@ -211,8 +211,8 @@ describe('Sample Files Integration', () => {
 	});
 
 	describe('Markdown files', () => {
-		it('should detect example secrets in readme.md', () => {
-			const content = readSampleFile('readme.md');
+		it('should detect example secrets in README.md', () => {
+			const content = readSampleFile('README.md');
 			const result = detectSecretsInContent(content, {
 				includeApiKeys: true,
 				sensitivity: 'medium',