feat(ai): pgvector embedding infrastructure (#19)

src/InboxIntel.Infrastructure/DependencyInjection.cs

@@ -21,10 +21,11 @@ public static class DependencyInjection
 {
     public static IServiceCollection AddInfrastructure(this IServiceCollection services, IConfiguration config)
     {
-        // EF Core / PostgreSQL
+        // EF Core / PostgreSQL. UseVector() enables pgvector mapping for the semantic-search
+        // embedding column (requires the 'vector' extension — added by the AddEmbeddingColumn migration).
         services.AddDbContext<AppDbContext>(opt =>
             opt.UseNpgsql(config.GetConnectionString("Postgres"),
-                npg => npg.MigrationsAssembly(typeof(AppDbContext).Assembly.FullName)));
+                npg => npg.MigrationsAssembly(typeof(AppDbContext).Assembly.FullName).UseVector()));
         services.AddScoped<IAppDbContext>(sp => sp.GetRequiredService<AppDbContext>());
 
         // Options