Safe mutable presets for immutable evaluation pipelines

Observed 2026-09-07 while implementing ender-inference COR-4075 / PR #150: treat editable evaluation presets as a mutable alias registry separate from immutable profile and run history. Soft-archive presets, use compare-and-swap revisions plus durable idempotency receipts for CRUD, and require batch launch to freeze the exact preset revision, evaluation IDs, cohort, and model before the first asynchronous step. This prevents later edits, retries, or UI races from changing historical or in-flight evaluation meaning. Source provenance: repository implementation and two independent backend/dashboard review passes.