[CHORE]: Move llmguardplugin to plugins/external/llmguard

Start by comparing plugins/external/llmguard/ in the source repository with the target repository, then copy the listed contents verbatim. Verify installation with pip install -e plugins/external/llmguard and run pytest plugins/external/llmguard/tests/. Done means the plugin is present, its README reflects the new home, and CI covers lint and tests.

Summary

Move the llmguardplugin external plugin from the mcp-context-forge monorepo into this repository at plugins/external/llmguard/, as part of the broader plugin ecosystem separation tracked in IBM/mcp-context-forge#2100.

What to move

Copy the contents of plugins/external/llmguard/ from IBM/mcp-context-forge verbatim:

plugins/external/llmguard/
├── .dockerignore
├── .env.template
├── .ruff.toml
├── Containerfile
├── MANIFEST.in
├── Makefile
├── README.md
├── cache_tokenizers.py
├── docker-compose.yaml
├── llmguardplugin/
│   ├── __init__.py
│   ├── cache.py
│   ├── llmguard.py
│   ├── plugin-manifest.yaml
│   ├── plugin.py
│   ├── policy.py
│   └── schema.py
├── examples/
├── pyproject.toml
├── resources/
├── run-server.sh
└── tests/

Dependencies (as-is)

From pyproject.toml:

llm-guard>=0.3.16
mcp>=1.28.1,<2
orjson>=3.11.9
rapidfuzz>=3.14.5
redis>=8.0.1

Note: mcp-contextforge-gateway is intentionally absent — it is a runtime-only dependency provided by the host gateway process and is not declared to avoid cryptography version conflicts with llm-guard's transitive dependency on presidio-anonymizer. This is documented in the existing pyproject.toml.

The plugin is moved as-is. Version constraint updates and the gateway dependency question are tracked separately (see sub-issues).

Acceptance criteria

• Plugin lands at plugins/external/llmguard/ in this repository
• pyproject.toml is present and installable (pip install -e plugins/external/llmguard)
• Existing tests pass (pytest plugins/external/llmguard/tests/)
• CI covers the plugin (lint + test)
• README updated to reflect new home

References

• Parent issue: IBM/mcp-context-forge#2100
• Source: https://github.com/IBM/mcp-context-forge/tree/main/plugins/external/llmguard