fix(identity): plan-statistics LINQ translation (aggregate in memory)

EF Core can't translate a conditional Count(predicate) inside a grouped Select;
fetch flat rows then group/aggregate in memory.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/identity/FlatRender.IdentitySvc/Application/Services/AdminService.cs

@@ -62,16 +62,20 @@ public class AdminService(IdentityDbContext db)
     public async Task<List<PlanStatRow>> GetPlanStatisticsAsync(Guid tenantId)
     {
         var now = DateTime.UtcNow;
-        return await db.UserPlans
+        // Pull flat rows then aggregate in memory — EF can't translate a conditional
+        // Count(predicate) inside a grouped Select.
+        var rows = await db.UserPlans
             .Where(p => p.TenantId == tenantId)
-            .GroupBy(p => p.PlanName)
+            .Select(p => new { p.PlanName, p.ExpiresAt, p.CancelledAt, p.PriceMinorPaid })
+            .ToListAsync();
+        return rows.GroupBy(r => r.PlanName)
             .Select(g => new PlanStatRow(
                 g.Key,
                 g.Count(),
                 g.Count(x => x.ExpiresAt > now && x.CancelledAt == null),
                 g.Sum(x => x.PriceMinorPaid)))
             .OrderByDescending(r => r.RevenueMinor)
-            .ToListAsync();
+            .ToList();
     }
 
     // ── CRM notes / tags ────────────────────────────────────────────────────