docs: PRD milestones with acceptance

docs/PRODUCT.md

@@ -40,7 +40,30 @@ A device draft in the app is separate from a WooCommerce draft.
 
 ## Milestones
 
-1. Capture — `docs/CAPTURE.md` (current increment). Ends when the user sees the inventory PNG and measurements. No Woo create.
-2. Review — remaining listing fields in the app
-3. Create — Woo draft for a practice SKU; then clear the device draft
-4. Assist — optional vision and generated copy on a working manual path
+Work is split into four milestones. Each milestone is done when its acceptance can be demonstrated.
+
+### Milestone 1 — Capture
+
+Spec: `docs/CAPTURE.md`. Current work.
+
+User stories:
+- Photograph a slab on a green or black sheet and remove the background.
+- Set length from the bounding rectangle and get widths, sqft, and bdft.
+- Leave and later Continue or Start fresh.
+
+Acceptance: inventory PNG and measurements visible on a phone. No Woo create.
+
+### Milestone 2 — Review
+
+Remaining listing fields in the app.
+Acceptance: every field in Complete listing is filled or proposed and editable.
+
+### Milestone 3 — Create
+
+WooCommerce draft for a practice SKU. Then clear the device draft.
+Acceptance: `SLAB-UAT-*` exists in the store as draft.
+
+### Milestone 4 — Assist
+
+Optional vision and generated copy on the manual path from Milestones 1–3.
+Acceptance: create still works with inference off.