docs(m3): close create contract gaps (soft delete, publish poll, prompts, image volume)

- R1 soft delete: add deleted_at to slabs; exclude deleted rows from GETs
- R2 publish: terminal poll returns woo_product_id then the working row is
  discarded; the app never deletes from WooCommerce (reworks PUBLISH-25)
- R3 prompts: SQLite is the point of record; file-based prompts superseded,
  compose prompt mount removed
- R4 images: photo bytes are SQLite BLOBs; /images is a health probe + staging

Details recorded in .audit/m3-build-plan.md.

docs/REQUIREMENTS.md

@@ -102,7 +102,7 @@ Sources reconciled 2026-09-18 from the current branch docs plus the `pre-simplif
 | PUBLISH-10 | SKUs matching SLAB-UAT-* always create a WooCommerce draft regardless of the create-status setting. | M3 | — |
 | PUBLISH-15 | A duplicate SKU blocks create and offers edit-SKU or open-existing; this version has no update path. | M3 | — |
 | PUBLISH-20 | A stale value on submit is a field-level error that shows the current options and never a raw code. | M3 | — |
-| PUBLISH-25 | On success the server sets woo_product_id, purges photos, deletes the local slab row, and clears the device draft; WooCommerce is the source of truth. | M3 | — |
+| PUBLISH-25 | On success the server sets woo_product_id and returns it on the terminal poll, purges photos, discards the local working slab row, and clears the device draft; the app never deletes from WooCommerce; WooCommerce is the source of truth. | M3 | — |
 | PUBLISH-30 | On failure the submission attempt is marked failed, photos are retained, sync_log is written, and a plain message is shown on the affected field or action; retry works from the same screen. | M3 | — |
 | PUBLISH-31 | If image uploads succeed but the product POST fails, the orphaned WooCommerce media is left in place, the failure is logged, and a manual cleanup note is surfaced; this version does not auto-delete it. | M3 | — |
 | PUBLISH-35 | The owner never sees raw status codes, stack traces, or internal error codes. | M3 | — |