feat(recommendations): refactor handler to use clean IVectorSearchStore abstraction and fix unit tests

src/NexusReader.Web/Program.cs

@@ -437,6 +437,20 @@ app.MapPost("/api/intelligence", async (
     return Results.BadRequest(errorMsg);
 }).RequireAuthorization();
 
+app.MapGet("/api/recommendations", async (
+    ClaimsPrincipal user,
+    IMediator mediator) =>
+{
+    var userId = user.FindFirstValue(ClaimTypes.NameIdentifier);
+    if (string.IsNullOrEmpty(userId)) return Results.Unauthorized();
+
+    var result = await mediator.Send(new NexusReader.Application.Queries.Recommendations.GetContextualRecommendationsQuery(userId));
+    if (result.IsSuccess) return Results.Ok(result.Value);
+
+    var errorMsg = result.Errors.Count > 0 ? result.Errors[0].Message : "Failed to fetch contextual recommendations";
+    return Results.BadRequest(errorMsg);
+}).RequireAuthorization();
+
 app.MapPost("/api/library/ingest", async ([FromBody] IngestEbookRequest request, ClaimsPrincipal user, IMediator mediator) =>
 {
     var userId = user.FindFirstValue(ClaimTypes.NameIdentifier);