feat: F4.6f2 the text editor on the document's Y.Text, files both ways while the simulation runs

Oracle TextEditorWindowRun uses Java's text editor window and its file
dialog as a person does. The open file's text is its Y.Text in the
document (plan 7.3): typed is in the file at once, for everyone and for
the running engine. Core openText/saveTextAs without Java's mistakes
(lost saves after save-as onto a file or a removed file, files named
'ordner/d.txt' or ''); doc files.ts (changeFiles, fileText, nodeFiles,
readFilesInto); the room takes a person's files into the engine at once
and writes the engine's files back at the tick they changed; the editor's
window, Java's dialog, the text area following others' changes with the
caret in place, its own undo.

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

packages/editor/src/desktop/desktop.css

@@ -809,3 +809,99 @@
 .mail-question button + button {
   margin-left: 8px;
 }
+
+/* The text editor (GUIApplicationTextEditorWindow): Java's four buttons
+ * above, the text below in Courier; 16 pixels, as Safari on the iPad zooms
+ * into smaller fields. */
+.text-editor {
+  position: relative;
+  flex: 1;
+  min-height: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 5px;
+  padding: 5px;
+  background: #eeeeee;
+}
+
+.text-editor-bar {
+  display: flex;
+  flex-wrap: wrap;
+  justify-content: center;
+  gap: 5px;
+  flex: none;
+}
+
+.text-editor-bar button,
+.file-dialog-folder button {
+  min-width: 44px;
+  min-height: 40px;
+  padding: 0 12px;
+  border: 1px solid #a0a0a0;
+  border-radius: 6px;
+  background: #f8f8f8;
+  color: #000000;
+  font: 13px Dialog, sans-serif;
+  cursor: pointer;
+}
+
+.text-editor-bar button:disabled,
+.file-dialog-folder button:disabled {
+  color: #a0a0a0;
+  cursor: default;
+}
+
+.text-editor-text {
+  flex: 1;
+  min-height: 0;
+  resize: none;
+  padding: 4px;
+  border: 1px solid #a0a0a0;
+  background: #ffffff;
+  color: #000000;
+  font: 16px 'Courier New', Courier, monospace;
+}
+
+/* Java's file dialog (DMTNFileChooser) over the program. */
+.file-dialog-folder {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  flex: none;
+}
+
+.file-dialog-folder span {
+  flex: 1;
+  min-width: 0;
+  overflow-wrap: anywhere;
+}
+
+.file-dialog-entries {
+  flex: 1;
+  min-height: 96px;
+  margin: 0;
+  padding: 0;
+  overflow: auto;
+  border: 1px solid #a0a0a0;
+  background: #ffffff;
+  list-style: none;
+}
+
+.file-dialog-entries button {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  width: 100%;
+  min-height: 32px;
+  padding: 0 6px;
+  border: 0;
+  background: transparent;
+  color: #000000;
+  font: 13px Dialog, sans-serif;
+  text-align: left;
+  cursor: pointer;
+}
+
+.file-dialog-entries button[aria-pressed='true'] {
+  background: #b8cfe5;
+}