initial: actor-test v0.1.0 — 8 assertions

Phase-A.5 test-lib for lib-core.actor. Covers create-validation
(missing/zero movement_speed loud-errors + valid spec), position
(initial x/y), move ((0,0) no-op + additive delta), movement_speed.

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

manifest.core

@@ -0,0 +1,6 @@
+{
+    "id": "lib-core.actor-test.core",
+    "kind": "lib",
+    "version": "0.1.0",
+    "license": "Proprietary"
+}