docs: allow UI/UX refinement before /generate-app (phase 3)

- README: add a refine loop (re-run /define-design or /update-design) between
  /define-design and /generate-app, in both Usage Workflow and the
  recommended workflow
- generate-app: note that it generates from the design as-is; refine first
- define-design: next steps now refine before generating code
- update-design: broaden to cover pre-generation refinement
- AGENTS.md: add the refine step to the initial setup flow

.opencode/command/define-design.md

@@ -171,6 +171,7 @@ 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
 - Use /update-design when a feature changes the UI
 - Use /add-feature to add features (it respects the design spec)

.opencode/command/generate-app.md

@@ -40,6 +40,7 @@ opencode
    - `docs/design/ui-blueprint.json`
    - `docs/design/platform-mapping.md`
 3. **Important**: Do **not** generate any platform-specific implementation before this command is executed. This command is the only place initial app scaffolding is created.
+4. This command generates from the design **as-is**. Refine the design first (re-run `/define-design` or use `/update-design <change>`) if anything needs to change — it is far easier to refine before code is generated than after.
 
 ## Procedure
 

.opencode/command/update-design.md

@@ -1,11 +1,11 @@
 ---
-description: Update the design spec when a feature request changes the UI (blueprint first, then tokens, brief, and SVGs)
+description: Refine the design before /generate-app, or update it when a feature changes the UI (blueprint first, then tokens, brief, and SVGs)
 agent: build
 ---
 
 # Update Design
 
-This command updates the design specification when a feature request changes the UI. It updates the structured design files **only** — it does **not** implement application code unless explicitly requested.
+This command updates the design specification. It is used in two situations: (1) to refine the UI/UX **before** running `/generate-app` (e.g. adjusting screens, tokens, or layout after reviewing the initial design), and (2) to update the design when a feature changes the UI. It updates the structured design files **only** — it does **not** implement application code unless explicitly requested.
 
 **Change description**: `$ARGUMENTS` (e.g. `/update-design add a profile screen with avatar and edit form`)