fix(ui): restore retail spell tabs and spellbook

Bind the spellbook and component-book tabs as their authored stateful text controls, propagate Closed/Open state into the retained DAT child tree, and keep authored label colors live across state changes.

Match retail UIElement_Text zero-margin construction so the Magic favorite captions I through VIII are no longer clipped. Add a real portal.dat spellbook fixture plus controller, state-propagation, and text-layout regression coverage.

Co-Authored-By: Codex <noreply@openai.com>

docs/research/2026-07-15-retail-magic-ui-and-casting-pseudocode.md

@@ -198,6 +198,43 @@ component item list            0x10000464
 component scrollbar            0x10000465
 ```
 
+The two top-level tabs are not `UIElement_Button` instances. They resolve from
+base `0x1000043A` as `UIElement_Text` (type 12), with state 11 `Closed` and
+state 12 `Open`. Both states set `PassToChildren`; the three child chrome
+elements carry the left/center/right Closed/Open RenderSurface media.
+
+Retail state and text construction used by these tabs:
+
+```text
+UIElement_Text::UIElement_Text @ 0x00468570
+    construct UIElement_Scrollable
+    bitField = 0x300                 // OneLine bit 0x2 is clear
+    horizontalJustification = 2
+    verticalJustification = 4
+    marginUp/Down/Left/Right = 0
+
+UIElement_Text::OnSetAttribute @ 0x0046A640
+    property 0x20 only:
+        SetOneLine(value)
+    // absent 0x20 therefore remains multi-line; do not force it true
+
+UIElement::SetState @ 0x00464E70
+    next = desc.AccessStateDesc(stateId)
+    if next != current:
+        current = next
+        if next.PassToChildren:
+            for each child:
+                child.SetState(stateId)
+        diff old/new effective properties
+        call OnSetAttribute for changed properties
+```
+
+The Magic-combat favorite tab captions are authored text (`I` through `VIII`)
+and intentionally omit property `0x20`. Their small rectangles still render
+because retail begins with zero text margins. A generic four-pixel inset on
+all sides leaves less than one DAT-font line and clips the captions completely;
+that inset is not retail behavior.
+
 Spellbook rows come only from the authoritative learned-spell set. Retail
 sorts by `CSpellBase::_display_order`; school and level buttons apply the
 server-persisted filter bitfield. Component rows use the installed component