feat(plugins): add promptfoo target discovery agent (#14)

Adds @crabcode/promptfoo plugin that:
- Analyzes target artifacts (curl, Burp, Postman, OpenAPI, text)
- Uses LLM agent loop to discover target communication
- Generates working promptfoo YAML configs
- Creates custom providers for complex targets (WebSocket, polling)
- Verifies configs with mini redteam tests

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Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: MrFlounder

plugins/promptfoo/.gitignore

@@ -0,0 +1,2 @@
+node_modules/
+dist/

plugins/promptfoo/bin/crab-pf.js

@@ -0,0 +1,2 @@
+#!/usr/bin/env node
+import '../dist/cli.js';