feat(ui): FA3 -- mount the social panel shell (Friends/Allegiance/Fellowship/Squelch)

Campaign FA slice FA3: retail's four-tab social panel (LayoutDesc
0x2100006E slot 0x1000018F, RetailPanelCatalog id 12), built on the OP3
OptionsPanelController recipe -- Type-8 tab host, ActivateTabBehavior,
per-page scoped controllers.

- SocialPanelController mounts the tab host and wires the close button;
  F3 (ToggleAllegiancePanel) and F4 (ToggleFellowshipPanel) open the
  panel and switch to their own tab, sharing the same gmPanelUI
  one-active-panel exclusivity every sibling main panel already has.
- The live-DAT tab table CORRECTS the coordinator addendum's x-order
  guess: button 0x1000028C ("Allegiance") pairs with page 0x10000291 and
  is the authored DEFAULT entry, not Friends -- each button's own page
  id and its own P0x57 (matching the F3/F4 ActionMap ids on the
  Allegiance/Fellowship pages specifically) both corroborate the real
  pairing. See SocialPanelController's class doc for the full table.
- SocialFellowshipPageController swaps the two authored empty/full
  frames (0x1000026B/0x10000275) on RuntimeFellowshipState's
  IsInFellowship -- both frames' full containment (name box, create
  button, checkboxes vs. roster list, six buttons) was confirmed by the
  live-mount probe, so a single Visible toggle per frame is the whole
  swap (closes lane-A unknown U6).
- SocialAllegiancePageController hides the monarch/patron blocks and
  blanks their name text to a literal space when
  RuntimeAllegianceState.Snapshot.HasProfile is false, using SCOPED
  FindDescendant lookups (the panel authors 0x10000492 twice, once per
  block).
- SocialFriendsPageController/SocialSquelchPageController bind their
  ListBoxes read-only to RuntimeCommunicationState's existing J4.1
  Friends/Squelch owners (names only), rebuilding on revision change.
  Their action buttons are honest INERT (D1) -- register row AD-79.
- UiTemplateListBox gains Flush() (lane A/D's "Gap found" prerequisite)
  so a poll-and-rebuild list can shrink between refreshes.
- RetailPanelCatalog.SocialPanel = 12, byte-verified from the live slot's
  own P0x10000029; listed in Mounted only (no toolbar button -- lane A
  §6.1: the open path is keyboard-only).

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

src/AcDream.App/UI/RetailPanelCatalog.cs

@@ -28,6 +28,20 @@ public static class RetailPanelCatalog
     /// </summary>
     public const uint Options = 10u;
 
+    /// <summary>
+    /// Campaign FA slice FA3: the four-tab Friends/Allegiance/Fellowship/
+    /// Squelch panel's <c>gmPanelUI</c> slot key — byte-verified from the
+    /// live installed DATs (host <c>0x2100006E</c> slot <c>0x1000018F</c>'s
+    /// own authored <c>0x10000029 = 12</c>, <c>FaPanelSlotProbeTests</c>).
+    /// No toolbar button authors this id (lane A §6.1: the open path is
+    /// keyboard-only, F3/F4) — <see cref="SocialPanel"/> is therefore in
+    /// <see cref="Mounted"/> only, not <see cref="Toolbar"/>, the same
+    /// convention <see cref="PositiveEffects"/>/<see cref="NegativeEffects"/>/
+    /// <see cref="LinkStatus"/>/<see cref="MiniGame"/>/<see cref="Vitae"/>
+    /// already use for their own non-toolbar open paths.
+    /// </summary>
+    public const uint SocialPanel = 12u;
+
     private static readonly (uint PanelId, string WindowName)[] Mounted =
     {
         (CharacterInformation, WindowNames.CharacterInformation),
@@ -40,6 +54,7 @@ public static class RetailPanelCatalog
         (Magic, WindowNames.Spellbook),
         (Vitae, WindowNames.Vitae),
         (Options, WindowNames.Options),
+        (SocialPanel, WindowNames.SocialPanel),
     };
 
     private static readonly (uint PanelId, string WindowName)[] Toolbar =