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/README.md

@@ -0,0 +1,18 @@
+# Usable LLM Keys Vault
+
+## Counts
+
+- **zhipu**: 207
+- **minimax**: 22
+- **volcanoark**: 22
+- **longcat**: 7
+- **codingplan**: 5
+- **deepseek**: 4
+- **dashscope**: 3
+- **freemodel**: 3
+- **xunfei**: 3
+- **siliconflow**: 2
+- **kiro**: 1
+- **mimo**: 1
+
+**Total: 280 keys across 12 providers**