Remove /generate-app: app shell is now milestone 01 of the plan

The initial app is no longer generated by a separate command. /plan-milestones
now always makes milestone 01 'App Shell Generation' (target platform asked in
the single question round): theme from design tokens, one screen per blueprint
entry, routes, reusable components — no feature logic — plus Playwright setup
and the e2e/app-shell.spec.ts smoke spec. It is executed like any other
milestone via /execute-milestones (which follows platform-ui-generation for it)
or /add-feature. Milestone 02 becomes the MVP core. All workflow diagrams,
skills, docs READMEs, AGENTS.md, and README updated; docs/design README also
gains the screen-inventory.md entry.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.opencode/command/define-design.md

@@ -24,11 +24,9 @@ opencode
   ↓
 /define-design        ← you are here
   ↓
-/generate-app web | flutter | winui3
+/plan-milestones      (milestone 01 = app shell, generated from this design)
   ↓
-/plan-milestones
-  ↓
-/add-feature
+/execute-milestones phase1-milestones.md   (or /add-feature per feature)
 ```
 
 ## Pre-Run Check
@@ -203,7 +201,7 @@ Design documents created:
 Next steps:
 - Review docs/design/ (especially ui-blueprint.json)
 - Refine the design with /update-design <change> (or re-run /define-design) until approved — do this BEFORE generating code
-- Run /generate-app web | flutter | winui3 to generate the initial app
+- Run /plan-milestones — milestone 01 (App Shell Generation) scaffolds the app from this design
 - Use /update-design when a feature changes the UI
 - Use /add-feature to add features (it respects the design spec)
 "