docs: redesign Roadmap as a native five-stage workflow

docs/strategy/roadmap.mdx

@@ -11,7 +11,7 @@ import ArchifyDiagram from '@site/src/components/ArchifyDiagram';
 
 Understand today’s code and how work really reaches production before introducing AI into the workflow. Fix what would make a pilot unsafe or impossible to evaluate—not every item of technical debt.
 
-<ArchifyDiagram name="strategy-roadmap" title="Assess code and delivery, improve readiness, pilot, expand on evidence, then sustain" story />
+<ArchifyDiagram name="strategy-roadmap" title="Understand today → Prepare foundations → Pilot → Expand → Sustain" story />
 
 **Recommended sequence · Target operating model, not an approved schedule or deployed governance.**