fix(lighting): indoor interiors now lit — landblock-key bug + viewer light + weenie fixtures

The whole "indoor interiors read dark/flat vs retail" saga was ONE root-cause
bug: EnvCellRenderer.GetCellLightSet derived the landblock key as
`cellId & 0xFFFF0000` (0xXXYY0000), but landblocks are keyed by the streaming
id 0xXXYYFFFF. The lookup missed for EVERY cell, so SelectForObject never ran
and every EnvCell wall received ZERO point lights — torches, lanterns, the
viewer light, all of it. Confirmed by a [cell-light] probe: inBounds=False
selected=0 across 1M+ cell draws; after the fix inBounds=True selected=3-4.
User-confirmed the interiors now look like retail.

Three faithful additions that were blocked by the key bug (and only show now):
- Viewer light (LightManager.UpdateViewerLight): retail's SmartBox::set_viewer
  (0x00452c40) adds a white fill light at the player every frame via
  add_dynamic_light — the dominant interior fill (no sun indoors). acdream had
  NO dynamic lights at all. Params from the cdb capture: intensity 2.25,
  falloff 10, white, offset (0,0,2). Indoor-only via the AP-43 gate.
- Weenie fixture lights (OnLiveEntitySpawnedLocked): server-spawned lanterns/
  braziers carry Setup.Lights but the dat-static registration never saw
  CreateObject entities. Register on spawn; unregister on despawn
  (UnregisterOwner made unconditional). Register row AP-44.
- IndoorObjectReceivesTorches now excludes the 0xFFFF landblock marker (it is
  not an EnvCell) — fixes WbDrawDispatcherIndoorFlagTests.LandblockId_OutdoorFlag0
  (a #142 verification miss).

Divergence register: AP-44 (weenie light spawn-position, no movement tracking),
AP-47 (acdream's 128-light/camera-independent cap keeps interiors always-lit vs
retail's 40-nearest-to-player budget that pops in on approach — intentional,
user-preferred).

Investigation: docs/research/2026-06-20-indoor-torch-lantern-lighting-investigation.md

Core 1505 / App 476 green. Visual gate: user-confirmed "looks like retail now."

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs

@@ -2107,7 +2107,9 @@ public sealed unsafe class WbDrawDispatcher : IDisposable
     /// <c>Render::useSunlight == 0</c>, which is true only in the indoor draw stage.
     /// </summary>
     internal static bool IndoorObjectReceivesTorches(uint? parentCellId)
-        => parentCellId.HasValue && (parentCellId.Value & 0xFFFFu) >= 0x0100u;
+        => parentCellId.HasValue
+           && (parentCellId.Value & 0xFFFFu) >= 0x0100u
+           && (parentCellId.Value & 0xFFFFu) != 0xFFFFu;   // 0xFFFF = landblock marker, not an EnvCell → outdoor
 
     /// <summary>
     /// Fix B: append the current entity's 8-slot light set to a group's