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>

tests/AcDream.App.Tests/UI/Layout/ConfigOptionsPageControllerTests.cs

@@ -930,7 +930,9 @@ public sealed class ConfigOptionsPageControllerTests
             DefaultOpacityDatDefault: 0.5f,
             ActiveOpacityDatDefault: 1.0f,
             CurrentFilter: _ => 0xFBFFFFFFul,
-            SetFilter: (_, _) => { });
+            SetFilter: (_, _) => { },
+            DefaultOpacityCaption: new ChatOptionsDatCaptions.Caption("Inactive Opacity", null),
+            ActiveOpacityCaption: new ChatOptionsDatCaptions.Caption("Active Opacity", null));
     }
 
     [Fact]