fix: pause blocked goal inspection loops

[selimerunkut]

Summary

Fixes #47.

An active goal can repeatedly requeue hidden continuations when the model is blocked and each run only calls get_goal before returning the same blocked summary. Because the goal remains active and incomplete, agent_end keeps calling maybeContinue(), creating an unbounded loop.

This change:

• detects runs whose only tool calls are get_goal or namespaced pi__get_goal;
• pauses the active goal with a clear user-attention reason instead of queuing another continuation;
• leaves normal runs with actionable tool calls unchanged;
• adds regression coverage and a changelog entry.

The goal remains incomplete and can be resumed explicitly after the user supplies the missing approval or decision.

Validation

• npm run verify
  • TypeScript typecheck passed.
  • Platform-smoke checks passed: 6/6.
  • Full test suite passed: 330/330.
• git diff --check passed.