feat(project): show presign counts as a statistics column

Group presign counts by project and team, include totals and unassigned rows, and reuse count drill-down. Remove the standalone footer while retaining presignTotal compatibility and the four formal business types.

Related to issue #13. Independent source review completed; no tests or builds run under user self-test arrangement.

backend/app/services/project_management.py

@@ -131,10 +131,11 @@ def records(db, tenant, user, biz_type, page=1, pageSize=20, **filters):
 def statistics(db, tenant, user, groupBy='project', **filters):
     if groupBy not in ('project', 'team'):
         raise HTTPException(400, '分组方式不支持')
-    totals = dict.fromkeys(COUNT_TYPES, 0)
-    unassigned = dict.fromkeys(COUNT_TYPES, 0)
+    statistics_types = ('presign', *COUNT_TYPES)
+    totals = dict.fromkeys(statistics_types, 0)
+    unassigned = dict.fromkeys(statistics_types, 0)
     counts = {}
-    for kind in COUNT_TYPES:
+    for kind in statistics_types:
         model = BUSINESS[kind][0]
         counts[kind] = filtered_query(db, tenant, user, kind, filters).with_entities(
             model.project_id, func.count(model.id)).group_by(model.project_id).all()
@@ -159,10 +160,10 @@ def statistics(db, tenant, user, groupBy='project', **filters):
             key = team_id if groupBy == 'team' else project_id
             item = items.setdefault(key, dict(id=key,
                 name=team_name if groupBy == 'team' else (info.project_name if info else None),
-                teamName=team_name, **dict.fromkeys(COUNT_TYPES, 0)))
+                teamName=team_name, **dict.fromkeys(statistics_types, 0)))
             item[kind] += count
     return dict(items=list(items.values()), totals=totals, unassignedTotals=unassigned,
-                presignTotal=filtered_query(db, tenant, user, 'presign', filters).count())
+                presignTotal=totals['presign'])
 
 
 def linked_records(db, tenant, user, kind, row_id, lock=False, current_read=False):