Adding mcp registry ASI04 challenge

[syedDS]

Fulfillment of #33

[syedDS]

ASI04: Insecure MCP (SSE) Registry Switch Challenge

Adds a new CTF challenge for detecting MCP registry manipulation and lack of provenance verification.

Files added:

finbot/ctf/definitions/challenges/mcp_security/insecure_registry_switch.yaml - Challenge definition (advanced, 300pts, OWASP LLM05/LLM07)
finbot/ctf/detectors/implementations/mcp_registry_switch.py - Detector with real-time (check_event) and on-demand (check_aggregate) detection by scanning vendor records and events for injected MCP config patterns
Files modified:

finbot/ctf/detectors/registry.py - Register new detector
.gitignore - Exclude challenge solution files

[saikishu]

This will be a great addition. I will be holding off on merging till we get our first MCP integrated into core codebase. After which we can test the attack path and assumptions.

[syedDS]

Based on the recent updates in admin panel in mcp config i see few integration gaps:

1. MCPRegistrySwitchDetector not registered , as finbot/ctf/detectors/implementations/init.py auto-discovers all detectors, but mcp_registry_switch.py is not imported → challenge can never be detected. You need to add it.

2. The challenge attack surface needs rethinking As the original challenge assumed a "registry URL" the attacker can change. The new architecture uses in-process servers there's no remote registry URL field anywhere. The realistic attack surface in the new codebase is the config_json of an MCP server ( eg: changing a payment URL, a storage endpoint, or adding a registry_url key via the admin portal config editor).

3. The check_aggregate detector searches vendor text fields.This won't work well with the new architecture. It should instead query MCPServerConfig records for the attacker's injected config.

I will figure solution and update the PR