Add AI tools example with SPIFFE identity and in-process OPA/WASM authorization

[oscerd]

What this adds

A new ai-tools-spiffe-opa example (category AI): a Camel LangChain4j agent whose tools are authorized before they run by an Open Policy Agent policy evaluated in-process as WebAssembly (the camel-opa wasm client), with SPIFFE (camel-spiffe) authenticating the calling workload.

The point is prompt-injection containment: a low-trust caller is talked into asking the model for a refund; the model tries the refundOrder tool, but the in-process guard denies it because that caller is not permitted, so no refund happens. A trusted caller is allowed to refund within a cap.

How it works

• Tools are Camel routes registered with the ai-tool component and driven by langchain4j-agent against a local Ollama model.
• The assistant validates each caller's JWT-SVID (SPIFFE) and keeps the caller identity as an exchange property, which Camel copies into every tool call and which the model cannot change.
• A shared route configuration evaluates opa/tools.rego, compiled to a WebAssembly bundle, in-process. evaluationMode=wasm means there is no OPA server and no network hop in the middle of the model's reasoning; the runtime is pure-Java (Chicory).
• There is deliberately no OPA server container: the policy runs inside the assistant.

Testing

• OpaWasmToolGuardTest exercises the real WebAssembly policy allowing/denying each case, fully offline (no LLM, no SPIRE). Runs with mvn verify.
• opa/tools_test.rego has Rego unit tests (opa test).
• A manual LlmToolCallingSmokeTest (disabled unless OLLAMA_SMOKE=true) drives the whole loop against a real Ollama model.
• Validated end to end with docker compose up (SPIRE + assistant + two callers, Ollama on the host): the public chatbot's prompt-injected refund is denied, the support console's refund is allowed.

Notes

• The WebAssembly policy bundle (src/main/resources/opa/tools-bundle.tar.gz) is checked in so the build and tests need no OPA toolchain; build-policy.sh rebuilds it from opa/tools.rego using the OPA container image. A RAT exclusion for **/src/main/resources/opa/*.tar.gz is added to the parent pom.
• See ai-tools-spiffe-opa/README.adoc for how to run it (including a local Ollama with a tool-capable model).