feat(rate-limiting): Implement core rate limiting functionality with configuration, decision-making, metrics, middleware, and service registration

- Add RateLimitConfig for configuration management with YAML binding support.
- Introduce RateLimitDecision to encapsulate the result of rate limit checks.
- Implement RateLimitMetrics for OpenTelemetry metrics tracking.
- Create RateLimitMiddleware for enforcing rate limits on incoming requests.
- Develop RateLimitService to orchestrate instance and environment rate limit checks.
- Add RateLimitServiceCollectionExtensions for dependency injection registration.

datasets/reachability/ground-truth/basic/gt-0001/main.c

@@ -0,0 +1,18 @@
+// gt-0001: Direct call to vulnerable sink from main
+// Expected: REACHABLE (tier: executed)
+// Vulnerability: CWE-120 (Buffer Copy without Checking Size)
+
+#include <stdio.h>
+#include <string.h>
+
+int main(int argc, char *argv[]) {
+    char buffer[32];
+    
+    if (argc > 1) {
+        // Vulnerable: strcpy without bounds checking
+        strcpy(buffer, argv[1]);  // SINK: CWE-120
+        printf("Input: %s\n", buffer);
+    }
+    
+    return 0;
+}