fix(userdata): read user data through to the database

The user data cache and the item's in-memory rows were both filled once per
replica and never invalidated, so a pod serving a playback tick read its own
stale resume position and wrote it back over the position another pod had just
saved, silently losing resume points, played state, favourites and ratings.

- drop the user item data cache
- read single and batched user data from the database on every query
- prefetch user data for in-memory sorts and filters so each stays one query
- cover the lost update against real PostgreSQL with two manager instances

tests/Jellyfin.Server.Implementations.Tests/Library/UserDataManagerTests.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Generic;
 using Emby.Server.Implementations.Library;
 using Jellyfin.Database.Implementations;
 using Jellyfin.Database.Implementations.Entities;
@@ -49,6 +48,12 @@ public sealed class UserDataManagerTests : IDisposable
         {
             Id = Guid.NewGuid()
         };
+
+        using (var ctx = CreateDbContext())
+        {
+            ctx.Users.Add(_user);
+            ctx.SaveChanges();
+        }
     }
 
     public void Dispose()
@@ -78,6 +83,23 @@ public sealed class UserDataManagerTests : IDisposable
         };
     }
 
+    private void Seed(AudioBook item, params UserData[] rows)
+    {
+        using var ctx = CreateDbContext();
+        ctx.BaseItems.Add(new BaseItemEntity { Id = item.Id, Type = typeof(AudioBook).FullName! });
+        ctx.UserData.AddRange(rows);
+        ctx.SaveChanges();
+    }
+
+    private User CreateOtherUser()
+    {
+        var user = new User("other", "auth-provider", "reset-provider") { Id = Guid.NewGuid() };
+        using var ctx = CreateDbContext();
+        ctx.Users.Add(user);
+        ctx.SaveChanges();
+        return user;
+    }
+
     private UserData CreateUserDataRow(AudioBook item, string key, long positionTicks)
     {
         return new UserData
@@ -98,11 +120,10 @@ public sealed class UserDataManagerTests : IDisposable
         var currentKey = item.GetUserDataKeys()[0];
 
         // the retired-key row comes first to ensure selection is by key, not row order
-        item.UserData = new List<UserData>
-        {
+        Seed(
+            item,
             CreateUserDataRow(item, "Author-Old Album-0001Old File Name", 111),
-            CreateUserDataRow(item, currentKey, 222)
-        };
+            CreateUserDataRow(item, currentKey, 222));
 
         var userData = _userDataManager.GetUserData(_user, item);
 
@@ -117,11 +138,10 @@ public sealed class UserDataManagerTests : IDisposable
         var item = CreateAudioBook();
         var idKey = item.GetUserDataKeys()[1];
 
-        item.UserData = new List<UserData>
-        {
+        Seed(
+            item,
             CreateUserDataRow(item, "Author-Old Album-0001Old File Name", 111),
-            CreateUserDataRow(item, idKey, 333)
-        };
+            CreateUserDataRow(item, idKey, 333));
 
         var userData = _userDataManager.GetUserData(_user, item);
 
@@ -135,10 +155,7 @@ public sealed class UserDataManagerTests : IDisposable
     {
         var item = CreateAudioBook();
 
-        item.UserData = new List<UserData>
-        {
-            CreateUserDataRow(item, "Author-Old Album-0001Old File Name", 111)
-        };
+        Seed(item, CreateUserDataRow(item, "Author-Old Album-0001Old File Name", 111));
 
         var userData = _userDataManager.GetUserData(_user, item);
 
@@ -150,7 +167,7 @@ public sealed class UserDataManagerTests : IDisposable
     public void GetUserData_NoRows_ReturnsDefaultWithPrimaryKey()
     {
         var item = CreateAudioBook();
-        item.UserData = new List<UserData>();
+        Seed(item);
 
         var userData = _userDataManager.GetUserData(_user, item);
 
@@ -166,13 +183,9 @@ public sealed class UserDataManagerTests : IDisposable
         var currentKey = item.GetUserDataKeys()[0];
 
         var otherUserRow = CreateUserDataRow(item, currentKey, 999);
-        otherUserRow.UserId = Guid.NewGuid();
+        otherUserRow.UserId = CreateOtherUser().Id;
 
-        item.UserData = new List<UserData>
-        {
-            otherUserRow,
-            CreateUserDataRow(item, currentKey, 222)
-        };
+        Seed(item, otherUserRow, CreateUserDataRow(item, currentKey, 222));
 
         var userData = _userDataManager.GetUserData(_user, item);
 
@@ -183,23 +196,15 @@ public sealed class UserDataManagerTests : IDisposable
     [Fact]
     public void GetUserDataBatch_DatabaseFallback_ResolvesRowsByKeyOrder()
     {
-        // no preloaded navigation data, so the batch takes the database fallback
         var fossilItem = CreateAudioBook();
         var retiredItem = CreateAudioBook();
 
-        using (var ctx = CreateDbContext())
-        {
-            ctx.Users.Add(_user);
-            ctx.BaseItems.Add(new BaseItemEntity { Id = fossilItem.Id, Type = typeof(AudioBook).FullName! });
-            ctx.BaseItems.Add(new BaseItemEntity { Id = retiredItem.Id, Type = typeof(AudioBook).FullName! });
-
-            // the stale id-key row is inserted first so selection by row order would return it
-            ctx.UserData.AddRange(
-                CreateUserDataRow(fossilItem, fossilItem.GetUserDataKeys()[1], 111),
-                CreateUserDataRow(fossilItem, fossilItem.GetUserDataKeys()[0], 222),
-                CreateUserDataRow(retiredItem, "Author-Old Album-0001Old File Name", 333));
-            ctx.SaveChanges();
-        }
+        // the stale id-key row is inserted first so selection by row order would return it
+        Seed(
+            fossilItem,
+            CreateUserDataRow(fossilItem, fossilItem.GetUserDataKeys()[1], 111),
+            CreateUserDataRow(fossilItem, fossilItem.GetUserDataKeys()[0], 222));
+        Seed(retiredItem, CreateUserDataRow(retiredItem, "Author-Old Album-0001Old File Name", 333));
 
         var result = _userDataManager.GetUserDataBatch([fossilItem, retiredItem], _user);