phase(N.5) Task 16: extend CLAUDE.md WB cribs with N.5 patterns

Adds four new bullets covering: the modern dispatch's three-SSBO +
multi-draw indirect layout; TextureCache.BindlessSupport contract +
parallel Texture2DArray upload path; two-pass alpha-test translucency
+ additive fallback plan; reserved per-instance highlight hook for
Phase B.4 follow-up.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -72,6 +72,34 @@ ourselves".
   `PrepareMeshDataAsync(id, isSetup)` to fire the background decode.
   Result auto-enqueues to `_stagedMeshData` which `Tick()` drains.
   `WbMeshAdapter` does this for you on first registration.
+- **N.5 modern dispatch** (`docs/superpowers/specs/2026-05-08-phase-n5-modern-rendering-design.md`)
+  uses bindless textures + multi-draw indirect on top of N.4's grouped
+  pipeline. Per frame: three SSBO uploads (`_instanceSsbo` mat4 per
+  instance @ binding=0; `_batchSsbo` `(uvec2 textureHandle, uint layer,
+  uint flags)` per group @ binding=1; `_indirectBuffer`
+  `DrawElementsIndirectCommand[]` opaque-section + transparent-section).
+  Two `glMultiDrawElementsIndirect` calls per frame, one per pass.
+  Total ~12-15 GL calls per frame for entity rendering regardless of
+  scene complexity.
+- **`TextureCache` requires `BindlessSupport`** for the WB modern path.
+  Three `Bindless`-suffixed `GetOrUpload*` methods return 64-bit handles
+  made resident at upload time, backed by parallel Texture2DArray uploads
+  (`UploadRgba8AsLayer1Array`). The legacy `uint`-returning methods stay
+  for Sky / Terrain / Debug / particle paths that still sample via
+  `sampler2D`. After N.6 retires legacy renderers, the legacy upload path
+  + caches can be deleted.
+- **Translucency model is two-pass alpha-test** (matches WB), not
+  per-blend-mode subpasses. Opaque pass discards `α<0.95`; transparent
+  pass discards `α≥0.95` AND `α<0.05`. Native `Additive` blend renders
+  as alpha-blend on GfxObj surfaces — falsifiable; if a magic-content
+  regression shows up, add a third indirect call with
+  `glBlendFunc(SrcAlpha, One)` per spec §6 fallback (~30 min change).
+- **Per-instance highlight (selection blink) is reserved.** `mesh_modern.vert`'s
+  `InstanceData` struct has a documented hook for `vec4 highlightColor`
+  — Phase B.4 follow-up adds the field + plumbs server-side selection
+  state. Stride grows from 64 → 80 bytes when added; shader updates
+  trivially (read the field from `Instances[instanceIndex]` + mix into
+  fragment color).
 
 **Execution phases:** R1→R8 in the architecture doc. Each phase has clear
 goals, test criteria, and builds on the previous. Don't skip phases.