fix(server-storage): keep a playlist id like __proto__ when filtering a read

withoutDeleted() builds its maps without a prototype, so a surviving
playlist whose id is __proto__ stays a key instead of changing the
object's prototype and losing its favorites and tag.

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

libs/services/src/lib/server-storage/server-user-data-edit.spec.ts

@@ -1,4 +1,4 @@
-import { applyEdit } from './server-user-data-edit';
+import { applyEdit, withoutDeleted } from './server-user-data-edit';
 
 describe('applyEdit', () => {
     it('adds the new favorite to what the server already has', () => {
@@ -59,3 +59,36 @@ describe('applyEdit', () => {
         expect(applyEdit(['x'], ['x'], undefined)).toBeUndefined();
     });
 });
+
+describe('withoutDeleted', () => {
+    it('drops deleted playlists and keeps every other id', () => {
+        const read = withoutDeleted(
+            {
+                entries: {
+                    'xtream-favorites': JSON.parse(
+                        '{"gone":["a"],"__proto__":["b"],"kept":["c"]}'
+                    ),
+                    'xtream-recent-items': {},
+                    'xtream-collection-items': {},
+                    'xtream-playback-positions': {},
+                },
+                tags: {
+                    'xtream-favorites': JSON.parse(
+                        '{"gone":"t1","__proto__":"t2","kept":"t3"}'
+                    ),
+                    'xtream-recent-items': {},
+                    'xtream-collection-items': {},
+                    'xtream-playback-positions': {},
+                },
+            },
+            ['gone']
+        );
+
+        expect(Object.keys(read.entries['xtream-favorites'])).toEqual([
+            '__proto__',
+            'kept',
+        ]);
+        expect(read.entries['xtream-favorites']['__proto__']).toEqual(['b']);
+        expect(read.tags?.['xtream-favorites']['__proto__']).toBe('t2');
+    });
+});

libs/services/src/lib/server-storage/server-user-data-edit.ts

@@ -161,7 +161,8 @@ export function withoutDeleted(
         return read;
     }
     const keep = <T>(map: Record<string, T> = {}): Record<string, T> => {
-        const kept: Record<string, T> = {};
+        // No prototype: a playlist id such as `__proto__` stays a key.
+        const kept: Record<string, T> = Object.create(null);
         for (const [id, value] of Object.entries(map)) {
             if (!deleted.some((gone) => gone === undefined || gone === id)) {
                 kept[id] = value;