feat(selection): port retail polygon picking and vivid marker

Replace the projected Setup-sphere rectangle and independent physics-wall ray with retail's render-coupled picker: only visible server-object parts participate, each exact drawing sphere broad-phases the camera-eye ray, and first-in-DAT-order visual polygon hits globally outrank sphere fallbacks.

Replace the devtools-only procedural triangles with the retained gameplay VividTargetIndicator using retail client-enum surfaces 1..4, radar-blip colorization, Setup selection-sphere framing, and the exact eight-pixel viewport clamp.

Release build succeeds with zero warnings and all 5,886 tests pass with five intentional skips.

Co-authored-by: OpenAI Codex <codex@openai.com>

docs/architecture/worldbuilder-inventory.md

@@ -400,6 +400,11 @@ WorldBuilder is a dat editor; it does not have:
 - **Audio** — OpenAL pipeline, sound triggers (we have this)
 - **TurbineChat** + **slash commands** (we have this)
 - **Login + character selection flow** (we have this)
+- **World-object mouse selection** — WorldBuilder supplies mesh/DAT access but
+  no retail client picker. Our narrow `RetailSelectionGeometryCache` reuses
+  `DatCollection` to expose each GfxObj drawing-BSP root sphere and visual
+  polygons; `WbDrawDispatcher` supplies the normal draw's current part
+  transforms to the named-retail selection accumulator.
 
 ---