fix: friends list live Online/Offline status - authored row state

machine + UiText per-state string swap (user retail gate)

The state side already worked (FriendsState replaces the full entry and
bumps Revision on 0x0021 OnlineStatus updates; the parser reads full
FriendData for every update type). The UI side had two gaps, exposed by
the installed-DAT row-template probe (template layout 0x2100005D root
0x10000519):

- The row authors TWO cells: the LEFT name text 0x1000051A whose
  Online (0x10000054) / Offline (0x10000055) PassToChildren states
  cascade into the RIGHT status grandchild 0x1000051F, which authors
  per-state 'Online'/'Offline' strings AND per-state colors (retail's
  green Online). The controller's FindDeepest binding wrote the NAME
  into the STATUS cell (the deepest text IS the status grandchild) and
  never flipped the state machine - so the status column never showed
  or updated anything.
- UiText had no per-state authored-string swap: ApplyDatState switched
  sprite + color per state but never the 0x17 string. Ported now
  (second consumer of the mechanism after the powerbar caption):
  DatWidgetFactory pre-resolves each state's authored string;
  TrySetRetailState swaps the line, colored by the SAME state's
  authored 0x1B.

SocialFriendsPageController now binds the name to its own cell and
flips the authored Online/Offline state per friend on every
Revision-driven rebuild - the cascade renders the status cell exactly
as retail's gmFriendsUI does, green Online included.

App suite 4,989/3 skips (new per-state swap conformance test).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/AcDream.App/UI/UiText.cs

@@ -293,6 +293,15 @@ public sealed class UiText : UiElement, IUiDatStateful
 
     public override string ActiveCursorStateName => _activeDatStateName;
 
+    private Dictionary<uint, string>? _authoredStateStrings;
+
+    /// <summary>Per-state authored strings (dat property 0x17 on the
+    /// element's OWN states, resolved at build by DatWidgetFactory).
+    /// <see cref="TrySetRetailState"/> swaps the displayed line when the
+    /// incoming state authors one — retail's state-cascade text swap.</summary>
+    internal void SetAuthoredStateStrings(Dictionary<uint, string> strings)
+        => _authoredStateStrings = strings;
+
     internal void ConfigureDatState(ElementInfo info)
     {
         _datInfo = info;
@@ -356,6 +365,18 @@ public sealed class UiText : UiElement, IUiDatStateful
             && TryColor(color, out Vector4 resolvedColor))
             DefaultColor = resolvedColor;
 
+        // Retail's state cascade also swaps the element's AUTHORED string
+        // when the incoming state carries its own 0x17 (the friends row's
+        // status cell: 'Online'/'Offline' with per-state colors). Resolved
+        // at build by DatWidgetFactory; single-line — no per-state multiline
+        // template exists in the authored set today. DefaultColor is read
+        // per call so THIS state's 0x1B (applied just above) colors it.
+        if (_authoredStateStrings is { } stateStrings
+            && stateStrings.TryGetValue(stateId, out string? authoredLine))
+        {
+            LinesProvider = () => [new Line(authoredLine, DefaultColor)];
+        }
+
         if (propagate && state?.PassToChildren == true)
         {
             foreach (UiElement child in Children)