fix(results-schema): include Language in unique constraint for CvMatchResults

The unique constraint on cvMatcher.Results was defined as (CvDocumentId, JobDocumentId)
but the code checks for (CvDocumentId, JobDocumentId, Language). This mismatch caused
duplicate key violations when matching the same CV+Job in different languages.

Update the constraint to (CvDocumentId, JobDocumentId, Language) to allow different
languages for the same CV+Job pair while preventing true duplicates.

Resolves: Duplicate key constraint violations on concurrent/repeated match requests

Apis/cv-matcher-data/Migrations/CvMatcherDbContextModelSnapshot.cs

@@ -88,7 +88,7 @@ namespace CvMatcher.Data.Migrations
 
                     b.HasKey("Id");
 
-                    b.HasIndex("CvDocumentId", "JobDocumentId")
+                    b.HasIndex("CvDocumentId", "JobDocumentId", "Language")
                         .IsUnique();
 
                     b.ToTable("Results", "cvMatcher");