Add database optimizations for photo search and pagination

Implement database-level sorting with composite indexes for efficient date and tag queries. Add pagination metadata support and optimize tag count queries using batch processing.

src/main.rs

@@ -527,6 +527,9 @@ async fn favorites(
             HttpResponse::Ok().json(PhotosResponse {
                 photos: favorites,
                 dirs: Vec::new(),
+                total_count: None,
+                has_more: None,
+                next_offset: None,
             })
         }
         Ok(Err(e)) => {