fix #380: Chat tab opacity sliders were missing their retail row captions

Root cause: PlayerOptionPage::AddSliderOption never sets a row's own
name-label text — the "Inactive Opacity"/"Active Opacity" caption comes
from a SEPARATE DAT-resident runtime catalog (DID 0x78000000, resolved
via the same two-level DBCache::GetDIDFromEnumStatic master-map/submap
lookup ChatOptionsDatDefaults already uses for enum 0x16/category 2,
here for enum 0x15/category 2) that nothing in the codebase ever
queried, so both slider rows rendered with no caption at all.

Fix: new ChatOptionsDatCaptions.TryRead resolves the DID-0x78000000
catalog's per-property name/tooltip entries (matched by the same
owning-property enum ChatOptionsDatDefaults already keys its defaults
by) and ChatOptionsPageController.BuildOpacitySliders stamps each
slider's own row caption/tooltip from it — falling back to no text
(never invented English) if resolution fails. Regressed by
ChatOptionsPageControllerTests.
Bind_WiresEachSlidersOwnRowCaption_FromTheResolvedDatCatalog and the
companion Bind_MissingCaption_RendersNoText_NeverInventsEnglish case,
plus a live-mount probe (OptionsPanelLiveMountProbeTests.
ProbeChatOpacityCaptions) confirming the production TryRead call
resolves "Inactive Opacity"/"Active Opacity" against the real DAT.

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

src/AcDream.App/UI/RetailUiRuntime.cs

@@ -2126,6 +2126,22 @@ public sealed class RetailUiRuntime : IDisposable
                     + "constructor values (0.5/1.0).");
             }
 
+            // #380: the two sliders' row CAPTIONS ("Inactive Opacity" /
+            // "Active Opacity") + tooltips — a SECOND, sibling DAT catalog
+            // lookup (DID 0x78000000, not the 0x78000001 defaults catalog
+            // above) — see ChatOptionsDatCaptions' own doc for the byte
+            // trace. Resolved once, same shape as the defaults read above.
+            if (!Layout.ChatOptionsDatCaptions.TryRead(
+                    _bindings.Assets.Dats, strings,
+                    out Layout.ChatOptionsDatCaptions.Caption defaultOpacityCaption,
+                    out Layout.ChatOptionsDatCaptions.Caption activeOpacityCaption))
+            {
+                Console.WriteLine(
+                    "[UI] options panel: Chat tab opacity slider captions did not resolve "
+                    + "(DID 0x78000000) — rows render with no caption rather than invented "
+                    + "English.");
+            }
+
             bool chatBound = Layout.ChatOptionsPageController.Bind(
                 layout,
                 controller.ChatPage,
@@ -2153,6 +2169,8 @@ public sealed class RetailUiRuntime : IDisposable
                     FlushOpacity: SaveChatOpacity,
                     DefaultOpacityDatDefault: datDefaultOpacity,
                     ActiveOpacityDatDefault: datActiveOpacity,
+                    DefaultOpacityCaption: defaultOpacityCaption,
+                    ActiveOpacityCaption: activeOpacityCaption,
                     CurrentFilter: windowId => _bindings.Chat.Windows.GetFilter(windowId),
                     SetFilter: (windowId, value) =>
                     {