Admin Decomposition: Rename delegate steps & add pre-processing for domain routes (Phase D)

[intel352]

Overview

~40 routes for domain services (Timeline, DLQ, AI, Components, Engine, Schema, Backfill, Billing, Replay) currently use name: forward as a meaningless step.delegate step. Replace with descriptive names and add optional pre-processing steps.

Reference: docs/ADMIN_CONFIG_DECOMPOSITION.md — Phase D
Depends on: Phase C (#87)

Domain Service Routes

Engine Management (→ admin-engine-mgmt) — 7 routes

get-engine-config, get-engine-status, list-engine-modules, list-engine-services, update-engine-config, validate-engine-config, reload-engine

Schema (→ admin-schema-mgmt) — 2 routes

list-schemas, list-module-schemas

AI (→ admin-ai-mgmt) — 6 routes

list-ai-providers, generate-workflow-from-intent, generate-component, suggest-improvements, deploy-generated-workflow, deploy-generated-component

Dynamic Components (→ admin-component-mgmt) — 5 routes

list-dynamic-components, get-dynamic-component, create-dynamic-component, update-dynamic-component, delete-dynamic-component

Timeline (→ admin-timeline-mgmt) — 3 routes

list-all-executions, get-execution-timeline, get-execution-events

Replay (→ admin-replay-mgmt) — 2 routes

replay-execution, get-replay-history

DLQ (→ admin-dlq-mgmt) — 7 routes

list-dlq-entries, get-dlq-stats, get-dlq-entry, retry-dlq-entry, discard-dlq-entry, resolve-dlq-entry, purge-resolved-dlq

Backfill/Mock/Diff (→ admin-backfill-mgmt) — 10 routes

list-backfills, create-backfill, get-backfill, cancel-backfill, list-mocks, set-step-mock, clear-all-mocks, list-pipeline-mocks, remove-step-mock, compute-execution-diff

Billing (→ admin-billing-mgmt) — 5 routes

list-billing-plans, get-usage-report, create-subscription, cancel-subscription, handle-billing-webhook

Files to Modify

• admin/config.yaml — rename ~40 delegate step names