test: Add secret detection benchmark dataset and ground truth

Add comprehensive benchmark dataset with 32 documented secrets for testing
secret detection workflows (gitleaks, trufflehog, llm_secret_detection).

- Add test_projects/secret_detection_benchmark/ with 19 test files
- Add ground truth JSON with precise line-by-line secret mappings
- Update .gitignore with exceptions for benchmark files (not real secrets)

Dataset breakdown:
- 12 Easy secrets (standard patterns)
- 10 Medium secrets (obfuscated)
- 10 Hard secrets (well hidden)

test_projects/secret_detection_benchmark/scripts/deploy.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+# Deployment script
+
+# MEDIUM SECRET #14: Secret in environment variable export
+export SECRET_API_KEY="sk_prod_1234567890abcdefghijklmnopqrstuvwxyz"
+
+echo "Deploying application..."
+
+# MEDIUM SECRET #15: URL-encoded secret in connection string (backup comment)
+# backup_connection="mysql://admin:MyP%40ssw0rd%21@db.example.com:3306/prod"
+
+deploy_app() {
+    echo "Deployment complete"
+}
+
+deploy_app

test_projects/secret_detection_benchmark/scripts/webhook.js

@@ -0,0 +1,13 @@
+// Webhook configuration and handlers
+
+// EASY SECRET #7: Slack webhook URL
+const SLACK_WEBHOOK = "https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXX";
+
+function sendSlackNotification(message) {
+    fetch(SLACK_WEBHOOK, {
+        method: 'POST',
+        body: JSON.stringify({ text: message })
+    });
+}
+
+module.exports = { sendSlackNotification };