Backend: table groups with prefix/color, auto-numbering, has_active_order flag

TableGroup gains prefix and color columns for display in the PWA zone filter.
Table creation now assigns a global auto-increment number; batch creation uses
group-local label numbering (avoids gaps/conflicts when adding to existing groups).
DELETE table now blocks if an active order exists (soft or hard delete).
Hard delete cascades past orders before removing the table row.
list_tables enriches each TableOut with has_active_order computed server-side.
TableOut no longer requires number in the input payload; TableCreate simplified.

Migration runner refactored to give each ALTER TABLE its own connection so a
no-op (column already exists) doesn't leave a dirty transaction blocking later
migrations. New migrations added for all new columns.

Order.print_logs relationship gains cascade="all, delete-orphan" so print logs
are removed when an order is deleted.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

local_backend/main.py

@@ -19,25 +19,29 @@ from routers import auth, tables, products, orders, waiters, reports, system
 
 
 def _run_migrations():
-    """Apply additive schema changes that create_all won't handle."""
+    """Apply additive schema changes that create_all won't handle.
+    Each migration gets its own connection so a no-op (column already exists)
+    doesn't leave a dirty transaction that blocks subsequent migrations."""
     from sqlalchemy import text
-    with engine.connect() as conn:
-        # Add extra_cost to product_ingredients if missing
+
+    migrations = [
+        "ALTER TABLE product_ingredients ADD COLUMN extra_cost REAL NOT NULL DEFAULT 0.0",
+        "ALTER TABLE products ADD COLUMN image_url VARCHAR",
+        "ALTER TABLE tables ADD COLUMN group_id INTEGER REFERENCES table_groups(id)",
+        "ALTER TABLE table_groups ADD COLUMN prefix VARCHAR",
+        "ALTER TABLE table_groups ADD COLUMN color VARCHAR",
+        "ALTER TABLE products ADD COLUMN sort_order INTEGER NOT NULL DEFAULT 0",
+        "ALTER TABLE product_preference_sets ADD COLUMN default_choice_id INTEGER",
+        "ALTER TABLE product_preference_choices ADD COLUMN sub_choices TEXT",
+        "ALTER TABLE product_preference_choices ADD COLUMN disables_subset INTEGER NOT NULL DEFAULT 0",
+        "ALTER TABLE product_preference_sets ADD COLUMN shared_subset TEXT",
+        "ALTER TABLE product_options ADD COLUMN sub_choices TEXT",
+    ]
+    for sql in migrations:
         try:
-            conn.execute(text("ALTER TABLE product_ingredients ADD COLUMN extra_cost REAL NOT NULL DEFAULT 0.0"))
-            conn.commit()
-        except Exception:
-            pass
-        # Add image_url to products if missing
-        try:
-            conn.execute(text("ALTER TABLE products ADD COLUMN image_url VARCHAR"))
-            conn.commit()
-        except Exception:
-            pass
-        # Add group_id to tables if missing (added in Phase 3 table groups)
-        try:
-            conn.execute(text("ALTER TABLE tables ADD COLUMN group_id INTEGER REFERENCES table_groups(id)"))
-            conn.commit()
+            with engine.connect() as conn:
+                conn.execute(text(sql))
+                conn.commit()
         except Exception:
             pass