perf(work-orders): batch attachment inserts and collapse photo updates

SaveAttachmentsAndPhotos committed once per attachment and re-fetched and
re-saved the work order once per photo field. Add AddWorkOrderAttachmentsAsync
for one commit, and load and save the work order once for all photo fields.
File storage stays per-file, since it is I/O rather than a database call.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Api.SeaHavenIndustries.Tests/WorkOrderDataServiceBatchingTests.cs

@@ -87,6 +87,34 @@ public class WorkOrderDataServiceBatchingTests
         context.WorkOrderAuditLogs.Should().HaveCount(2);
     }
 
+    [Fact]
+    public async Task AddWorkOrderAttachmentsAsync_PersistsAllRowsInSingleSave()
+    {
+        await using var context = NewContext();
+        await SeedAsync(context);
+        var service = new WorkOrderDataService(context);
+
+        await service.AddWorkOrderAttachmentsAsync(new[]
+        {
+            new WorkOrderAttachments { WorkorderId = 1, Attachments = "https://files/a.pdf" },
+            new WorkOrderAttachments { WorkorderId = 1, Attachments = "https://files/b.pdf" }
+        });
+
+        context.workOrderAttachments.Should().HaveCount(2);
+    }
+
+    [Fact]
+    public async Task AddWorkOrderAttachmentsAsync_WithEmptyCollection_DoesNothing()
+    {
+        await using var context = NewContext();
+        await SeedAsync(context);
+        var service = new WorkOrderDataService(context);
+
+        await service.AddWorkOrderAttachmentsAsync(Array.Empty<WorkOrderAttachments>());
+
+        context.workOrderAttachments.Should().BeEmpty();
+    }
+
     [Fact]
     public async Task GetByIdsOrderedAsync_PreservesInputOrderDeduplicatesAndSkipsMissing()
     {

SeaHaven.DataServices/Implementation/WorkOrderDataService.cs

@@ -288,6 +288,15 @@ namespace SeaHaven.DataServices.Implementation
             await _context.SaveChangesAsync();
         }
 
+        public async Task AddWorkOrderAttachmentsAsync(IReadOnlyCollection<WorkOrderAttachments> attachments)
+        {
+            if (attachments.Count == 0)
+                return;
+
+            await _context.workOrderAttachments.AddRangeAsync(attachments);
+            await _context.SaveChangesAsync();
+        }
+
         public async Task AddAuditLogAsync(WorkOrderAuditLog auditLog)
         {
             await _context.WorkOrderAuditLogs.AddAsync(auditLog);

SeaHaven.DataServices/Interfaces/IWorkOrderDataService.cs

@@ -57,6 +57,8 @@ namespace SeaHaven.DataServices.Interfaces
         Task AddWorkOrderContactsAsync(int workOrderId, IEnumerable<int> contactIds);
         Task AddWorkOrderCategoriesAsync(int workOrderId, IEnumerable<int> categoryIds);
         Task AddWorkOrderAttachmentAsync(WorkOrderAttachments attachment);
+        /// <summary>Adds every attachment in one commit (no per-row round trip).</summary>
+        Task AddWorkOrderAttachmentsAsync(IReadOnlyCollection<WorkOrderAttachments> attachments);
         Task AddAuditLogAsync(WorkOrderAuditLog auditLog);
         Task AddAuditLogsAsync(IReadOnlyCollection<WorkOrderAuditLog> auditLogs);