Adopt CultMath in Aetheria and drop Unity.Mathematics from Studio drawers

Operator decision: Aetheria moves onto CultMath as the best workout GameCult's
math library can get, with gaps filled in CultMath itself. The map no longer
rejects the switch, and Cut 6's Studio drawers target CultMath types only.
Unity.Mathematics stays permitted for tooling supporting a Unity game; CultLib
uses CultMath.

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

docs/cultcache-migration-cut.md

@@ -87,7 +87,13 @@ C# implements it (Cut 3); TS, Rust and Python delete their mirror paths
 ### Q2. How do Unity.Mathematics values encode portably?
 
 **As fixed-length positional arrays of components, Aetheria's existing wire
-shape `[P5]`. CultMath defines no encoding and is not adopted.**
+shape `[P5]`. CultMath defines no encoding and is not adopted.** (Superseded
+2026-09-14: Aetheria adopts CultMath, the operator's decision for dogfooding
+GameCult's math library. The same positional-array encoding applies to CultMath
+types, and gaps found by the parity audit are filled in CultMath rather than
+worked around in Aetheria. Unity.Mathematics stays licensed for tooling that
+supports a Unity game under the Unity Companion License; CultLib itself uses
+CultMath only.)
 
 - Aetheria writes `float2` as `[f32,f32]`, `float3` three, `float4` four,
   `int2` `[int,int]`, `bool2` `[bool,bool]`
@@ -1307,8 +1313,9 @@ the behavior change.
   built-ins for `IDictionary` (recursive keys and values, add/remove), abstract
   or interface members (subtype popup from the member type's `[MessagePack.Union]`
   attributes only), `CultRecordRef<T>` (popup of documents assignable to `T` by
-  `[CultName]`, plus the raw key); the reflective struct path kept for
-  Unity.Mathematics and CultMath (operator-verified). Unclaimed types render a
+  `[CultName]`, plus the raw key); vector and matrix drawers target CultMath
+  types only, and the Studio package takes no Unity.Mathematics dependency.
+  Unclaimed types render a
   visible error row.
 - Verification: batchmode compile of `src\GameCult.Unity`; then the operator
   opens a `.cc` with each member kind, edits, saves, and confirms open-then-close
@@ -1622,7 +1629,7 @@ Rejected paths:
 - Per-field `[MessagePackFormatter]` attributes; `Dictionary<string, float>`
   instead of ref-keyed maps; a list of pairs.
 - A `storeId` in the file header; a save converter; a `DatabaseEntry` `ID`
-  shim; switching `ServerShared` to CultMath; union tags for `RequireBehavior`;
+  shim; union tags for `RequireBehavior`;
   a JSON intermediate or `extern alias` for the import; the GameCult generator
   in `Aetheria.Shared`; persisting agent tasks.