feat(ui): spellcasting cast-button + character-panel attribute/skill tooltips — gmSpellcastingUI::UpdateCastButtonTooltip @0x004C6A30, AttributeInfoRegion/Attribute2ndInfoRegion/SkillInfoRegion @0x004F1530/0x004F1680/0x004F2140

TS-85 remainder batch (hover/UI overnight round, batch B). Audit found
three of the four listed spellcasting SetTooltip sites (endowment icon,
favorite, submenu) were already correct via UiCatalogSlot's pre-existing
Label-driven GetTooltipText; only the cast button (UiButton, no tooltip
wiring at all) was a real gap. Ports the verified literal states
("Select a spell to cast" / "You have no spells ready to cast" / the
full endowment-item USE-the-%s branch) plus a documented, narrower
fallback (spell name only) for the one sub-branch whose exact wording
sits behind a genuine gmNoticeHandler vtable-slot collision in the
pseudo-C dump rather than the unlabeled-string-pool class the rest of
this batch recovered.

Character panel: new UiClickablePanel.TooltipText seam (same pattern as
UiButton.TooltipText) carries the six hardcoded attribute descriptions
and three pair-shared vitals descriptions (byte-decoded from the retail
string pool) plus skill tooltips composed from the already-DAT-parsed
SkillBase.Description/.Formula — no hand-transcription needed for the
~30+ skill strings. The formula-to-text algorithm itself
(SkillSystem::InqSkillFormula) was recovered by byte-decoding six short
fragments Binary Ninja left completely unlabeled between two
gmSpellcastingUI vtable declarations.

Live-verified against the local ACE server: 34 real skills' composed
tooltips and both reachable cast-button states captured via a temporary
probe (stripped before this commit). Full solution suite green
(14,647 tests, 0 failures) both before and after the probe strip.

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

src/AcDream.App/UI/UiPanel.cs

@@ -152,6 +152,20 @@ public class UiClickablePanel : UiPanel
     /// Ignored when <see cref="UseSelectionBars"/> is false.</summary>
     public float SelectionBarHeight { get; set; } = 3f;
 
+    /// <summary>Settable tooltip, surfaced through the shared
+    /// <see cref="UiElement.GetTooltipText"/> hover pipeline (same pattern as
+    /// <see cref="UiButton.TooltipText"/> / <see cref="UiCatalogSlot"/>). TS-85's
+    /// character-panel gap: retail's <c>AttributeInfoRegion</c> /
+    /// <c>Attribute2ndInfoRegion</c> / <c>SkillInfoRegion</c> row constructors
+    /// (<c>UIElement::SetTooltip</c> at 0x004f1617 / 0x004f1777 / 0x004f222f) stamp
+    /// this once per row at construction — retail never updates it afterward, so a
+    /// plain settable string (not a live provider) matches.</summary>
+    public string? TooltipText { get; set; }
+
+    /// <inheritdoc />
+    public override string? GetTooltipText() =>
+        string.IsNullOrWhiteSpace(TooltipText) ? null : TooltipText;
+
     public UiClickablePanel()
     {
         // Rows must receive pointer events — override the UiPanel default (ClickThrough=false,