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/volcanoark/PLAN_SUMMARY.txt

@@ -0,0 +1,13 @@
+VolcanoArk key plan classification (verified via model-access matrix):
+
+  CODING+AGENT+PAYGO      : 14 keys
+  AGENT+PAYGO             : 2 keys
+  AGENT                   : 2 keys
+  PAYGO                   : 1 keys
+  CODING+PAYGO            : 1 keys
+  CODING+AGENT            : 1 keys
+  CODING                  : 1 keys
+
+TOTAL USABLE: 22 / 32
+Plan tags: CODING = seed-code coding models; AGENT = seed-2.1/1.8/deepseek-v4 agent models; PAYGO = standard doubao-pro billing.
+Verified: 2026-08-01 13:26 UTC