fix: fleet config issues from 2026-07-18 relay review

- hermes-agent-baseline: add gpu-dense and gpu-light to models list
- hermes-config-template: fix pgrep traps (exclude infisical wrapper) + add
  vault empty-key guard documentation in Rule 13
- litellm-api-keys: fix pgrep pattern in auditable check
- scripts/agent-health-check: fix pgrep to exclude infisical bash wrapper

Addresses issues found during relay inbox resolution session:
1. pgrep -f 'hermes_cli.main gateway run' matches both the real python
   gateway and the infisical bash wrapper, causing false health readings
2. infisical vault stores empty key silently — no guard/monitoring
3. gpu-dense/gpu-light stable aliases missing from baseline config

hermes-agent-baseline.prose.md

@@ -193,6 +193,8 @@ Key is injected via `infisical run --` wrapper at PM2 startup:
       "models": [
         { "id": "syslog-auto" },
         { "id": "strix-moe" },
+        { "id": "gpu-dense" },
+        { "id": "gpu-light" },
         { "id": "qwen3.6-27B-code" },
         { "id": "gemma-4-12b" }
       ]