[rennf93]

ktor-guard's code already accepts an injected agent handler, but through the engine it never worked. guard-core-jvm only added an agent to its telemetry composite when it was a HandlerAgentSink, which guard-agent-jvm's GuardAgentTelemetry is not. The agent was therefore never started and received no events. That is fixed in Guard-Core/guard-core-jvm#48 (merged as 9067b7b).

This PR:

• Moves the pinned engine ref to 9067b7b (CI, CodeQL, release workflow, settings and docs).
• Adds InjectedAgentWiringTest:
  • The degrade path without a handler.
  • An injected GuardAgentTelemetry-shaped handler is started, receives events and metrics (metrics via sendMetric), and is stopped on shutdown().
    Against the old pin, the second test fails with expected: <1> but was: <0>.

Local gate: ./gradlew build passes (37 tests, 0 failures) against guard-core-jvm 9067b7b. Nothing is released.

[github-actions]

Thanks for opening your first pull request on ktor-guard!

Quick checklist before review (most of these are enforced by CI, but worth a glance):

• The PR body says Closes #N for an open issue (the issue-link check enforces it); chores take the no-issue label
• ./gradlew spotlessCheck detekt is clean
• ./gradlew build passes
• No blanket @Suppress in non-test code

See README.md for the adapter status. Welcome aboard - a maintainer will review shortly.