feat(graph): node library as a docked panel; shared dock chrome

The node library leaves the overlay and becomes a dock panel (PanelId::
NodeGraph), docked on the right the first time the graph opens and movable
like any other panel; closing it closes the graph. It follows the block
palette's layout: title bar, then a search box with New / Open / Save
beside it, then the categories, of which only Objects starts open. Entries
are clicked (placed at the canvas top-left) or dragged onto the canvas.

The title bar (title, auto-collapse pin, close, drag to re-dock), the
toolbar icon button and the panel frame were copied across Properties,
Block Palette, External References and Browser; they are now
dock::title_bar, dock::tool_button and dock::frame, used by all of them.
Block Palette's two tool buttons gain tooltips, and External References'
Auto / Close tooltips are now translated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/update/dialog.rs

@@ -605,6 +605,9 @@ pub(super) fn on_ribbon_tool_click(&mut self, tool_id: String, event: ModuleEven
                     PanelId::Browser => {
                         self.show_browser = false;
                     }
+                    PanelId::NodeGraph => {
+                        self.show_node_graph = false;
+                    }
                     PanelId::Properties => {
                         self.show_properties = false;
                         self.ribbon.set_properties(false);
@@ -708,6 +711,7 @@ pub(super) fn on_ribbon_tool_click(&mut self, tool_id: String, event: ModuleEven
             PanelId::BlockPalette => self.show_block_palette,
             PanelId::ExternalReferences => self.show_external_references,
             PanelId::Browser => self.show_browser,
+            PanelId::NodeGraph => self.show_node_graph,
         }
     }