Add folder anatomy (scripts/agent.py + references/api-reference.md) for 648 cybersecurity skills

Complete skill folder anatomy across all cybersecurity skills:
- scripts/agent.py: 80-150 line Python agents using real libraries (impacket,
  boto3, azure-mgmt-*, kubernetes, pefile, yara, scapy, shodan, stix2, etc.)
- references/api-reference.md: real API documentation with method signatures
- LICENSE: MIT license for all skill folders

skills/implementing-api-rate-limiting-and-throttling/references/api-reference.md

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+# API Reference: Implementing API Rate Limiting and Throttling
+
+## Token Bucket Algorithm
+
+```python
+import time
+class TokenBucket:
+    def __init__(self, capacity, refill_rate):
+        self.capacity = capacity
+        self.tokens = capacity
+        self.refill_rate = refill_rate  # tokens/sec
+        self.last_refill = time.time()
+
+    def allow(self):
+        now = time.time()
+        self.tokens = min(self.capacity,
+            self.tokens + (now - self.last_refill) * self.refill_rate)
+        self.last_refill = now
+        if self.tokens >= 1:
+            self.tokens -= 1
+            return True
+        return False
+```
+
+## Redis Sliding Window
+
+```python
+import redis, time
+r = redis.Redis()
+def check_rate(client_id, window=60, limit=100):
+    key = f"rl:{client_id}"
+    now = time.time()
+    pipe = r.pipeline()
+    pipe.zremrangebyscore(key, 0, now - window)
+    pipe.zadd(key, {str(now): now})
+    pipe.zcard(key)
+    pipe.expire(key, window)
+    _, _, count, _ = pipe.execute()
+    return count <= limit
+```
+
+## HTTP 429 Response Headers
+
+| Header | Value | Description |
+|--------|-------|-------------|
+| `Retry-After` | `30` | Seconds until retry |
+| `X-RateLimit-Limit` | `100` | Max requests |
+| `X-RateLimit-Remaining` | `0` | Remaining requests |
+| `X-RateLimit-Reset` | epoch | Reset timestamp |
+
+## Kong Rate Limiting Plugin
+
+```bash
+curl -X POST http://localhost:8001/services/{id}/plugins \
+  -d "name=rate-limiting" \
+  -d "config.minute=100" \
+  -d "config.policy=redis" \
+  -d "config.redis_host=redis"
+```
+
+### References
+
+- Redis Rate Limiting: https://redis.io/glossary/rate-limiting/
+- IETF RateLimit Headers: https://datatracker.ietf.org/doc/draft-ietf-httpapi-ratelimit-headers/
+- Kong Rate Limiting: https://docs.konghq.com/hub/kong-inc/rate-limiting/