HU1: complete panel test imports after main integration

Restore the explicit names required by the upstream panel-docking tests and format the imports. All test bodies and assertions are byte-for-byte unchanged. fmt, pdf-deps and clippy pass; 3,375 tests pass, with four font/Georgian findings documented in the PR and six ignored. The remaining i18n-report, doctest, assets, layers and 16 WASM checks pass. One worker under a 2 GiB memory guard.

crates/ui-egui/src/panel_docking_tests.rs

@@ -1,5 +1,8 @@
-use super::{DesignApp, Layout, Node, cancel_gesture, json, valid};
-use crate::panel_docking::{area_id, close_visible, default_layout, dock_columns, hit_id, icon_column, in_iconic_column, layout_of, modal_open, open_window_drops, panel_menu, set_iconic, showing, tab_group, tab_id, window_groups};
+use super::{Column, DesignApp, Floating, Layout, Node, Side, Value, cancel_gesture, json, valid};
+use crate::panel_docking::{
+    CANVAS, DOCK_LABELS, ICON_GROUPS, PanelContent, Placed, area_id, close_visible, default_layout, dock_columns, hit_id, icon_column,
+    in_iconic_column, layout_of, modal_open, open_window_drops, panel_menu, set_iconic, showing, tab_group, tab_id, window_groups,
+};
 use egui::{Event, Modifiers, PointerButton, Pos2, vec2};
 use egui_kittest::{Harness, kittest::Queryable};