Fix assistant KB MCP tool names

[jorisjonkers-dev-agents]

Summary

• Switch assistant-api's knowledge MCP adapter to the canonical dot-form knowledge.recall and knowledge.capture_lesson tool names.
• Parse MCP JSON-RPC responses from raw strings so the thin adapter does not depend on RestClient's JsonNode converter behavior.
• Add focused request/response tests for recall, capture, and disabled RAG behavior.

Verification

• ./gradlew :services:assistant-api:test
• ./gradlew :services:assistant-api:ktlintCheck :services:assistant-api:detekt

Not run

• ./gradlew :services:assistant-api:integrationTest could not complete because Testcontainers could not find a Docker environment (/var/run/docker.sock missing).