ALF pipeline for processing a single agentic loop iteration.

Given an LLM response that may contain tool calls, this pipeline:

1. ParseToolCalls — Extracts tool calls from the response
2. ValidateCalls — Checks names exist, validates args vs schema
3. BudgetGuard — Iteration budget enforcement
4. DispatchTools — Executes tools via the resolver, collects results
5. InjectResults — Builds tool result messages for the next turn
6. LoopDecision — Decides {:continue, msgs} or {:done, response}

This is the per-iteration counterpart to the outer loop in LlmCore.Agent.Loop. The relationship mirrors the pattern of an outer iteration controller wrapping a per-event processing pipeline:

GrooveExecutor.run_steps        ↔  LlmCore.Agent.Loop.run
Stepwise.Pipeline.Stepwise      ↔  LlmCore.Agent.Pipeline.Iteration
StepwiseAction / Advance / etc. ↔  ParseToolCalls / Dispatch / etc.