perf(db): add remaining hot-path indexes (status filter, correspondence/event FKs)

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

Data/JobTrackerContext.cs

@@ -71,6 +71,11 @@ namespace JobTrackerApi.Data
         modelBuilder.Entity<JobApplication>()
             .HasIndex(j => new { j.OwnerUserId, j.FollowUpAt });
 
+        // Board/list endpoints that filter by both IsDeleted and Status. Same MySQL
+        // longtext-prefix caveat as above; the reconciler applies `Status(50)` there.
+        modelBuilder.Entity<JobApplication>()
+            .HasIndex(j => new { j.OwnerUserId, j.IsDeleted, j.Status });
+
         modelBuilder.Entity<Company>()
             .HasIndex(c => c.OwnerUserId);
 
@@ -81,6 +86,9 @@ namespace JobTrackerApi.Data
             .HasForeignKey(c => c.JobApplicationId)
             .OnDelete(DeleteBehavior.Cascade);
 
+        modelBuilder.Entity<Correspondence>()
+            .HasIndex(c => c.JobApplicationId);
+
         modelBuilder.Entity<GmailConnection>()
             .HasQueryFilter(x => CurrentUserId != null && x.OwnerUserId == CurrentUserId);
 
@@ -111,6 +119,9 @@ namespace JobTrackerApi.Data
             .HasForeignKey(e => e.JobApplicationId)
             .OnDelete(DeleteBehavior.Cascade);
 
+        modelBuilder.Entity<JobEvent>()
+            .HasIndex(e => e.JobApplicationId);
+
         modelBuilder.Entity<CvUploadArtifact>()
             .HasQueryFilter(x => CurrentUserId != null && x.OwnerUserId == CurrentUserId);