docs: add changelog entry for System Use Cases workflow restructuring

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: raifdmueller

docs/changelog.adoc

@@ -2,6 +2,12 @@
 
 A chronological record of all semantic anchors added to the catalog. Community contributors are credited with thanks.
 
+== 2026-05-03
+
+*Workflow improvements:*
+
+* *Specification workflow restructured* — Step 4 now builds the spec in layers: Persona Use Cases (Cockburn Fully Dressed, User Goal level), System Use Cases (technical interfaces: API, CLI, events, file formats), and Supplementary Specifications (Entity Model, State Machines, Interface Contracts, Validation Rules). Aligned with Martinelli's AIUP distinction between Business and System Use Case Specifications.
+
 == 2026-05-02
 
 *New anchors:*