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/results/live/china/volcano-ark-coding-plan/README.md

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+# Volcano Engine Ark - Coding Plan (Anthropic-compatible)
+
+## Endpoint
+POST https://ark.cn-beijing.volces.com/api/coding/v1/messages
+
+## Auth
+Header: x-api-key: <UUID>
+Header: anthropic-version: 2023-06-01
+
+## Usable Keys & Models
+
+### Key: 209bcbe8-3cdf-4397-b13c-2323e481af82
+Source: https://github.com/LiuTianjie/yishu-knowledge/blob/fa0d5b52bc8f2e255aca361004ada0fca37dfc27/.env
+
+Models (all confirmed usable):
+- claude-sonnet-4-6
+- claude-opus-4-6
+- claude-haiku-3-5
+- claude-3-5-haiku-20241022
+- claude-3-haiku-20240307
+- claude-sonnet-4-20250514
+- claude-opus-4-20250514
+- claude-3-7-sonnet-20250219
+- doubao-seed-2-0-pro-260215
+
+## Usage Example
+```bash
+curl -s https://ark.cn-beijing.volces.com/api/coding/v1/messages \
+  -H "x-api-key: 209bcbe8-3cdf-4397-b13c-2323e481af82" \
+  -H "anthropic-version: 2023-06-01" \
+  -H "Content-Type: application/json" \
+  -d '{"model":"claude-sonnet-4-6","messages":[{"role":"user","content":"hi"}],"max_tokens":100}'
+```

tools/scripts/llm-key-hunter/results/live/china/volcano-ark-coding-plan/key.txt

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+209bcbe8-3cdf-4397-b13c-2323e481af82