feat(03-03): add OpenRouter, LiteLLM, Cloudflare, Vercel, Portkey, Helicone gateways

- sk-or-v1- and sk-helicone- high-confidence prefix regex
- LiteLLM low-confidence sk- pattern with master key keyword
- Cloudflare, Vercel, Portkey keyword-anchored detection

pkg/providers/definitions/helicone.yaml

@@ -0,0 +1,21 @@
+format_version: 1
+name: helicone
+display_name: Helicone
+tier: 5
+last_verified: "2026-04-05"
+keywords:
+  - "helicone"
+  - "HELICONE_API_KEY"
+  - "sk-helicone-"
+  - "api.helicone.ai"
+patterns:
+  - regex: 'sk-helicone-[a-z0-9]{7}-[a-z0-9]{7}-[a-z0-9]{7}-[a-z0-9]{7}'
+    entropy_min: 3.5
+    confidence: high
+verify:
+  method: GET
+  url: https://api.helicone.ai/v1/key/verify
+  headers:
+    Authorization: "Bearer {KEY}"
+  valid_status: [200]
+  invalid_status: [401, 403]