test: add integration test for all_pending_tools_resolved? gating with multiple tool calls

[BlueHotDog]

Context

When an agent issues multiple tool calls in a single response, the agent should NOT resume until ALL tool results have arrived. Interaction.all_pending_tools_resolved?/1 implements this check, but no integration test verifies the gating behavior with partial results.

Missing Invariant

With N pending tool calls:

• Submitting N-1 results: agent must NOT resume, all_pending_tools_resolved? returns false
• Submitting the Nth result: agent resumes, all_pending_tools_resolved? returns true

Proposed Test

1. Start an agent that issues 2+ interactive tool calls
2. Submit a result for only the first tool call
3. Assert the agent is still blocked (running but waiting)
4. Submit a result for the second tool call
5. Assert the agent resumes and eventually completes

File

apps/frontman_server/test/frontman_server/tasks/execution_test.exs