perf: 优化 Material 可用物料过滤，改为 DB 子查询

- 新增 filter_process_todo 过滤器替代原 todo tag 逻辑
- 避免将 ID 列表加载到 Python 内存，改用两个子查询 OR 合并

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

apps/mtm/filters.py

@@ -1,12 +1,13 @@
 from django_filters import rest_framework as filters
-from apps.mtm.models import Goal, Material, Route, RoutePack
+from apps.mtm.models import Goal, Material, Route, RouteMat, RoutePack, Process
 from django.db.models.expressions import F
 from rest_framework.exceptions import ParseError
 from django.db.models import Sum, Q, Value, F, ExpressionWrapper, DecimalField
 from django.db.models.functions import Coalesce
 
 class MaterialFilter(filters.FilterSet):
-    tag = filters.CharFilter(method='filter_tag', label="low_inm:库存不足")
+    tag = filters.CharFilter(method='filter_tag', label="low_inm:库存不足;todo:可用")
+    process_todo = filters.CharFilter(method='filter_process_todo', label="process_todo:待处理")
 
     class Meta:
         model = Material
@@ -25,6 +26,14 @@ class MaterialFilter(filters.FilterSet):
             "route_material_out__mgroup": ["exact"],
             "count_safe": ["gte", "lte", "exact", "gt", "lt"]
         }
+    
+    def filter_process_todo(self, queryset, name, value):
+        if value:
+            queryset = queryset.filter(
+                Q(id__in=RouteMat.objects.filter(route__process__id=value).values('material_id')) |
+                Q(id__in=Route.objects.filter(process__id=value).values('material_in_id'))
+            )
+        return queryset
 
     def filter_tag(self, queryset, name, value):
         if value == 'low_inm':