Restore compact Changes diff controls (#1945)

* feat(app): restore compact Changes diff controls

Keep the folder tree behind a view toggle while preserving the flat file list as the default.

Move secondary diff options into the overflow menu so the Changes toolbar stays compact.

* fix(app): mirror whitespace diff option copy

* fix(app): polish diff controls review follow-up

packages/app/src/hooks/use-changes-preferences/storage.test.ts

@@ -28,6 +28,7 @@ describe("loadChangesPreferencesFromStorage", () => {
 
     expect(result).toEqual({
       layout: "unified",
+      viewMode: "flat",
       wrapLines: true,
       hideWhitespace: false,
     });
@@ -37,6 +38,7 @@ describe("loadChangesPreferencesFromStorage", () => {
   it("loads persisted layout and whitespace preferences without rewriting storage", async () => {
     const persisted = JSON.stringify({
       layout: "split",
+      viewMode: "tree",
       hideWhitespace: true,
       wrapLines: false,
     });
@@ -48,6 +50,7 @@ describe("loadChangesPreferencesFromStorage", () => {
 
     expect(result).toEqual({
       layout: "split",
+      viewMode: "tree",
       hideWhitespace: true,
       wrapLines: false,
     });
@@ -64,11 +67,16 @@ describe("saveChangesPreferences", () => {
 
     await saveChangesPreferences({
       queryClient,
-      updates: { layout: "split", hideWhitespace: true },
+      updates: { layout: "split", viewMode: "tree", hideWhitespace: true },
       storage,
     });
 
-    const expected = { ...DEFAULT_CHANGES_PREFERENCES, layout: "split", hideWhitespace: true };
+    const expected = {
+      ...DEFAULT_CHANGES_PREFERENCES,
+      layout: "split",
+      viewMode: "tree",
+      hideWhitespace: true,
+    };
     expect(queryClient.getQueryData(CHANGES_PREFERENCES_QUERY_KEY)).toEqual(expected);
     expect(storage.entries.get(CHANGES_PREFERENCES_STORAGE_KEY)).toBe(JSON.stringify(expected));
   });

packages/app/src/hooks/use-changes-preferences/storage.ts

@@ -7,18 +7,21 @@ export const CHANGES_PREFERENCES_QUERY_KEY = ["changes-preferences"];
 
 const changesPreferencesSchema = z.object({
   layout: z.enum(["unified", "split"]).optional(),
+  viewMode: z.enum(["flat", "tree"]).optional(),
   wrapLines: z.boolean().optional(),
   hideWhitespace: z.boolean().optional(),
 });
 
 export interface ChangesPreferences {
   layout: "unified" | "split";
+  viewMode: "flat" | "tree";
   wrapLines: boolean;
   hideWhitespace: boolean;
 }
 
 export const DEFAULT_CHANGES_PREFERENCES: ChangesPreferences = {
   layout: "unified",
+  viewMode: "flat",
   wrapLines: false,
   hideWhitespace: false,
 };