ENG-1626 Pre-fill Create node dialog with selected text

When the "Create discourse node" command is triggered with text selected
in the editor, pass it as initialTitle to ModifyNodeModal so the title
field is pre-filled — matching the existing behaviour of the right-click
context menu.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: trangdoan982

apps/obsidian/src/utils/registerCommands.ts

@@ -94,15 +94,15 @@ export const registerCommands = (plugin: DiscourseGraphPlugin) => {
     id: "create-discourse-node",
     name: "Create discourse node",
     callback: () => {
-      const currentFile =
-        plugin.app.workspace.getActiveViewOfType(MarkdownView)?.file ||
-        undefined;
-      const editor =
-        plugin.app.workspace.getActiveViewOfType(MarkdownView)?.editor;
+      const activeView = plugin.app.workspace.getActiveViewOfType(MarkdownView);
+      const currentFile = activeView?.file || undefined;
+      const editor = activeView?.editor;
+      const selectedText = editor?.getSelection()?.trim() || undefined;
       new ModifyNodeModal(plugin.app, {
         nodeTypes: plugin.settings.nodeTypes,
         plugin,
         currentFile,
+        initialTitle: selectedText,
         onSubmit: createModifyNodeModalSubmitHandler(plugin, editor),
       }).open();
     },