Remove duplicate definitions from executor.ts and pi-runtime.ts that
already live in executor-*.ts and pi-model-config.ts. Import extracted
symbols with .js extensions and re-export the public executor/pi-runtime
surface for existing callers.
Export a few pi-model-config helpers required by pi-runtime (including
boundAgentToolResult and toolCallBudgetFor) and align beginToolCall queue
typing with AgentRuntimeEvent.
Co-authored-by: cynarAI <cynarAI@users.noreply.github.com>