Docs-Sync #371: misplaced DTO summary, plus a Stats rollup key the admin settings section does not own #375

Source PR: #371 (Precompute dashboard statistics into hourly buckets)

Affected surfaces: src/NodePilot.Api/Dtos/WorkflowDtos.cs, src/NodePilot.Api/Configuration/SettingsSections.cs, docs/claude-reference.md, src/nodepilot-docs-ui/content/{de,en}/configuration/retention.md.

The drift this run could apply on its own is in #376 (the three new hosted services were missing from both background-service inventories). The findings below were left alone.

• src/NodePilot.Api/Dtos/WorkflowDtos.cs: the <summary> block describing one row of GET /api/workflows — including the paragraph on HasManualTriggerParameters — now sits directly above the newly inserted WorkflowNameItem record, which therefore carries two consecutive <summary> blocks, while WorkflowListItemResponse is left undocumented. The doc comment describes a type it is no longer attached to. Not auto-applied: this is a source file, outside a docs-only sync; moving the comment back is a code change.
• Stats:Rollup:Enabled is read by ExecutionStatsRollupService, but the Stats admin-settings section in SettingsSections.cs declares only Stats:RefreshIntervalMinutes and Stats:WindowDays. The key is therefore documented and file-settable but not reachable from the Admin UI. Not auto-applied: whether it belongs in SettingsSchema/SettingsSections (and what a Stats settings save does to a hand-edited Stats:Rollup:Enabled in appsettings.runtime.json) is a product decision, not a doc correction. Dashboard:Warmup:Enabled has the same status and no section at all.
• Pre-existing, not caused by Precompute dashboard statistics into hourly buckets #371 — the background-services table in docs/claude-reference.md is introduced as covering the hosted services, but six registered ones have never been listed: AuthSessionCleanupService, DatabaseAvailabilityProbe, DirectorySynchronizationService, ExternalAuthorizationStalenessService, ThreadPoolTuningService and SignalRExecutionNotifier. The docs-site mirror (configuration/retention.md, "Other background services") omits the same ones. Not auto-applied: whether those tables are meant to be exhaustive or a curated operator subset is a human call, and guessing wrong makes the inventory misleading in the other direction.

Automated docs-drift finding from the nightly documentation-sync run; needs triage.