fix(master-data): never let Item master-data abort migrate

On a bare/half-provisioned site (e.g. a distrobuilder base image where standard
UOMs like 'Litre' are not loaded yet), Item insert raised LinkValidationError
and the unhandled exception aborted the whole `bench migrate`, failing the
image build.

Isolate each Item insert in a savepoint and catch failures: roll back just that
item, log a visible SKIPPED line, and continue. Items are only inserted when
missing, so a later migrate on a fully provisioned site still creates them.
Adds a 'failed' counter to the summary line.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

taxes_az/master_data/sync.py

@@ -263,7 +263,7 @@ def sync_items() -> dict:
 
     root = _resolve_item_group_root()
     print(f"[taxes_az] Item: resolved tree root = {root!r}, {len(records)} shipped item(s)")
-    inserted = existed = missing_group = 0
+    inserted = existed = missing_group = failed = 0
 
     for rec in records:
         name = rec.get("name") or rec.get("item_code")
@@ -282,6 +282,14 @@ def sync_items() -> dict:
             missing_group += 1
             continue
 
+        # Isolate each insert in a savepoint: on a bare/half-provisioned site a
+        # missing link (e.g. UOM 'Litre') raises LinkValidationError, and an
+        # unhandled exception here would abort the whole `bench migrate`. Master
+        # data must never do that — roll back just this item and carry on. The
+        # item stays missing and a later migrate (once the site is complete)
+        # will create it, since sync only inserts items that don't exist yet.
+        frappe.db.savepoint("taxes_az_item")
+        try:
             doc = frappe.new_doc("Item")
             doc.update(rec)
             doc.item_group = group
@@ -289,6 +297,13 @@ def sync_items() -> dict:
             doc.flags.name_set = True
             doc.flags.ignore_permissions = True
             doc.insert(ignore_if_duplicate=True)
+        except Exception as e:
+            frappe.db.rollback(save_point="taxes_az_item")
+            frappe.clear_last_message()
+            print(f"[taxes_az] Item '{name}': insert FAILED — SKIPPED ({e})")
+            failed += 1
+            continue
+        frappe.db.release_savepoint("taxes_az_item")
         print(f"[taxes_az] Item: created {name!r} ({rec.get('item_name')}) in {group!r}")
         inserted += 1
 
@@ -296,13 +311,14 @@ def sync_items() -> dict:
         frappe.db.commit()
     print(
         f"[taxes_az] Item: created {inserted}, already existed {existed}, "
-        f"skipped (missing group) {missing_group}"
+        f"skipped (missing group) {missing_group}, failed {failed}"
     )
     return {
         "doctype": "Item",
         "inserted": inserted,
         "existed": existed,
         "missing_group": missing_group,
+        "failed": failed,
     }