feat: F4.6f3 the file explorer and the image viewer

Oracle FileExplorerWindowRun uses Java's explorer and viewer windows as a
person does (the right-click menu, Java's questions answered, the import
window, the viewer's open). Both windows work on the document's files
through the core's operations: the tree of folders and files, the chosen
folder's entries, Java's menu (also as buttons, no right click needed),
copy that stays and cut that goes once pasted, the import; the viewer's
picture and title. Not taken from Java: a file chosen in the tree taken
for a folder, pictures laid over each other, a text file as an empty
picture. writeFiles numbers the entries in the file system's order again
when a rename made a new key.

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

packages/core/test/filePrograms.test.ts

@@ -24,6 +24,7 @@ import {
   saveText,
   saveTextAs,
   openText,
+  openImage,
   VirtualFileSystem,
   type Clipboard,
   type PageLanguage,
@@ -265,4 +266,18 @@ describe('the file programs beyond the cases', () => {
     expect(saveTextAs(files, '/', 'ORDNER', 'e')).toBe('isFolder');
     expect(files.allEntries().map((entry) => entry.path)).toEqual(['/', '/ordner', '/ordner/d.txt']);
   });
+
+  // Measured with FileExplorerWindowRun (packages/sim/test/fileExplorerWindow.java.json).
+  it("opens an image by the dialog's folder and name, in any case, and neither another file nor what is not there", () => {
+    const files = new VirtualFileSystem();
+    files.createDirectory('/webserver');
+    files.writeImageFile('/webserver/Bild.png', new Uint8Array([1, 2]), 'image/png');
+    files.writeTextFile('/text.txt', 'x');
+    expect(openImage(files, '/webserver', 'bild.PNG')).toEqual({ path: '/webserver/Bild.png', data: new Uint8Array([1, 2]), mediaType: 'image/png' });
+    expect(openImage(files, '/', 'webserver/Bild.png')).toEqual(openImage(files, '/text', '/webserver/Bild.png'));
+    expect(['fehlt.png', '', 'webserver'].map((name) => openImage(files, '/', name))).toEqual(['notFound', 'notFound', 'notFound']);
+    expect(openImage(files, '/', 'text.txt')).toBe('notImage');
+    files.writeBinaryFile('/daten.bin', new Uint8Array([3]));
+    expect(openImage(files, '/', 'daten.bin')).toBe('notImage');
+  });
 });