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;
+}

datasets/reachability/ground-truth/basic/gt-0001/sample.manifest.json

@@ -0,0 +1,29 @@
+{
+  "$schema": "https://stellaops.io/schemas/sample-manifest.v1.json",
+  "sampleId": "gt-0001",
+  "version": "1.0.0",
+  "category": "basic",
+  "description": "Direct call to vulnerable sink from main - REACHABLE",
+  "language": "c",
+  "expectedResult": {
+    "reachable": true,
+    "tier": "executed",
+    "confidence": 1.0
+  },
+  "source": {
+    "files": ["main.c"],
+    "entrypoint": "main",
+    "sink": "strcpy",
+    "vulnerability": "CWE-120"
+  },
+  "callChain": [
+    {"function": "main", "file": "main.c", "line": 5},
+    {"function": "strcpy", "file": "<libc>", "line": null}
+  ],
+  "annotations": {
+    "notes": "Simplest reachable case - direct call from entrypoint to vulnerable function",
+    "difficulty": "trivial"
+  },
+  "createdAt": "2025-12-17T00:00:00Z",
+  "createdBy": "corpus-team"
+}