fix(migrations): make runner robust for all tenant DBs

- Register all missing migrations in runner.py
- Make v4.3 idempotent (rename xml_unsigned only if exists)
- Make v3.3 idempotent (skip warehouse_inventory/purchase_order_items ops when tables/columns missing)
- Mark v3.3.1 and v3.9 as master-only (SKIP)
- Mark v3.5.1 as optional (skip if whatsapp tables missing)
- Runner skips files marked with '-- : SKIP'

pos/migrations/runner.py

@@ -77,11 +77,19 @@ def apply_migration(db_name, version):
         print(f"  ERROR: Migration file not found: {filepath}")
         return False
 
+    with open(filepath) as f:
+        sql = f.read()
+
+    # Skip migrations marked for manual/non-tenant execution
+    first_line = sql.splitlines()[0].strip() if sql.strip() else ''
+    if first_line.startswith(': SKIP') or first_line.startswith('-- : SKIP'):
+        print(f"  SKIP (manual/non-tenant migration)")
+        return True
+
     conn = get_tenant_conn_by_dbname(db_name)
     cur = conn.cursor()
     try:
-        with open(filepath) as f:
-            cur.execute(f.read())
+        cur.execute(sql)
         conn.commit()
         return True
     except Exception as e: