fix(usage): export filtered events and fix dark mode contrast

Export every request matching the current filters, remember the selected page size, and use dark surfaces for filter menus and request cards.

src-tauri/src/usage.rs

@@ -4255,7 +4255,7 @@ fn load_usage_events(
         .map(from_sql_i64)
         .map_err(|error| format!("Failed to count SQLite usage events: {error}"))?
         .min(usize::MAX as u64) as usize;
-    let page_size = query.page_size.unwrap_or(50).clamp(20, 200);
+    let page_size = query.page_size.unwrap_or(50).clamp(1, 5_000);
     let total_pages = total.div_ceil(page_size).max(1);
     let page = query.page.unwrap_or(1).clamp(1, total_pages);
     let offset = (page - 1).saturating_mul(page_size);
@@ -6544,6 +6544,13 @@ mod tests {
         assert_eq!(analysis.models[0].key, "gpt-5.6-terra");
         assert_eq!(events.total, 1);
         assert_eq!(events.items[0].id, "request-2");
+        let exported = load_usage_events(
+            &connection,
+            &UsageQuery { page_size: Some(5_000), ..query },
+            &config,
+        ).unwrap();
+        assert_eq!(exported.page_size, 5_000);
+        assert_eq!(exported.items.len(), 1);
         drop(connection);
         fs::remove_dir_all(root).unwrap();
     }