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/cn_extra/all_usable.txt

@@ -0,0 +1 @@
+MiMo|sk-cx8s34vwo7n1j79mm5l07228ib6x3tfkqdtzz17rxf96p0x0|https://github.com/Wjs226213/obsidian/blob/e5bf1ea61d734fcd4060e44ab4c225cc8d245f68/js-Note/.claudian/claudian-settings.json|[mimo-v2.5] 200 {"id":"c1ec15eb-8662-4a6e-8918-3be251335d1d_5b58b04edeb24a4fb949eabb836f1574","choices":[{"finish_re