edit page: styleguide-driven layout + pricing_mode debug log

UI (per fox: "use styleguide to make this edit page way way better"):
- div.edit-page now max-width 1200px, centered, with token-based gap
- wells get larger internal padding (--space-4 + --space-5) so content
  isn't crammed against the well edge
- well h3:first-child resets margin-top and uses 1.125rem / 600 weight
- fieldsets inside edit page get tokens-based border, padding, legend
  styling that matches the rest of the design system

Debug:
- TEMPORARY log line in product_edit pricing_mode handler logs the raw
  POST params for the pricing_mode field plus the submit value. Will
  remove once the prod save-revert issue is diagnosed. Fox reports
  saving "Make an offer with buy-now" reverts to fixed price; cannot
  reproduce locally. Log will show whether the form is sending the
  field at all when fox saves.

Total: tests still pass (9 pricing_mode + 15 in target slice).

make_post_sell/static/css/common.css

@@ -1311,7 +1311,10 @@ img.serp-thumbnail {
 div.edit-page {
     display: grid;
     grid-template-columns: 1fr;
-    grid-gap: 20px;
+    gap: var(--space-4, 16px);
+    max-width: 1200px;
+    margin: 0 auto;
+    padding: var(--space-3, 12px);
 }
 
 @media (min-width: 720px) {
@@ -1320,6 +1323,37 @@ div.edit-page {
     }
 }
 
+/* Wells on the edit page get more breathing room than the default. */
+div.edit-page > section.well2 {
+    padding: var(--space-4, 16px) var(--space-5, 20px);
+}
+
+div.edit-page > section.well2 > h3:first-child,
+div.edit-page > section.well2 > form > h3:first-child {
+    margin-top: 0;
+    font-size: 1.125rem;
+    font-weight: 600;
+}
+
+/* Pricing-mode fieldset on edit page — improved spacing. */
+div.edit-page fieldset {
+    border: 1px solid var(--color-border, #ddd);
+    border-radius: var(--radius-md, 8px);
+    padding: var(--space-3, 12px) var(--space-4, 16px);
+    margin: var(--space-3, 12px) 0;
+}
+
+div.edit-page fieldset legend {
+    padding: 0 var(--space-2, 8px);
+    font-weight: 600;
+    color: var(--color-text-muted, #666);
+}
+
+div.edit-page fieldset label[style*="display:block"],
+div.edit-page fieldset label.visibility_radio {
+    line-height: 1.6;
+}
+
 hr {
   color: var(--border-light, #EEEEEE);
 }

make_post_sell/views/product.py

@@ -313,6 +313,22 @@ def product_edit(request):
 
     # MPS-20 + MPS-21: pricing_mode + allow_offers (per-product overrides).
     if "submit" in request.params:
+        # TEMPORARY DEBUG: log raw POST params for pricing_mode investigation.
+        # Remove once the save defect is diagnosed.
+        try:
+            import logging as _logging
+            _logging.getLogger(__name__).warning(
+                "PRICING_MODE_DEBUG product=%s current=%s pricing_mode_param=%r "
+                "all_pricing_mode=%r submit=%r",
+                product.uuid_str,
+                product.pricing_mode,
+                request.params.get("pricing_mode"),
+                request.params.getall("pricing_mode")
+                    if hasattr(request.params, "getall") else "no-getall",
+                request.params.get("submit"),
+            )
+        except Exception:
+            pass
         try:
             new_mode = int(request.params.get("pricing_mode", product.pricing_mode))
         except (TypeError, ValueError):