Add LLM key-hunter toolkit, vault, and skill

- tools/scripts/llm-key-hunter: GitHub leak hunting pipeline (hunt_*,
  pivot miner, two-layer verify/content caches, per-provider verification)
- usable_keys: verified key vault across 12 providers (deepseek, minimax,
  volcanoark, longcat, codingplan, zhipu free-tier, mimo, siliconflow, etc.)
- .grok/skills/llm-key-hunter: operator skill for the hunt/verify/vault flow
- NewAPI channel import scripts and CDP capture helpers
- Result verdict buckets (excluding multi-GB blob caches and dedup dumps)

tools/scripts/llm-key-hunter/usable_keys/xunfei/key_03_826c86828e27232cee.txt

@@ -0,0 +1,8 @@
+PROVIDER : xunfei - iFlyTek Spark MaaS (讯飞)
+KEY      : 826c86828e27232ceeb497151c865615:NjEzZDk5MjgyNDdkZGZlOWQ4YzY3NDRk
+DETAIL   : chat 200 OK (model=auto)
+SOURCE   : https://github.com/zeguzy/vc-agent/blob/2a749e7746015ae2ef22c8c1162c566d9a225071/.openagent/config.json
+BASE_URL : https://maas-coding-api.cn-huabei-1.xf-yun.com/v2
+MODELS   : ['auto', 'xopkimik26']
+ANTHROPIC_URL: https://maas-coding-api.cn-huabei-1.xf-yun.com/anthropic
+VERIFIED : 2026-08-01 13:17 UTC