feat(scala): m01–m06 port with shared fixtures

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

scala/test/M03Rules.test.scala

@@ -0,0 +1,31 @@
+package snake
+
+import Fixtures.*
+
+class M03RulesSuite extends munit.FunSuite:
+  cases("m03-move").foreach { c =>
+    test(s"move: ${c("name").str}") {
+      val a = c("args")
+      assertEquals(Rules.move(point(a(0)), direction(a(1))), point(c("expected")))
+    }
+  }
+
+  cases("m03-in-bounds").foreach { c =>
+    test(s"inBounds: ${c("name").str}") {
+      val a = c("args")
+      assertEquals(Rules.inBounds(gameState(a(0)), point(a(1))), c("expected").bool)
+    }
+  }
+
+  cases("m03-turn").foreach { c =>
+    test(s"turn: ${c("name").str}") {
+      val a = c("args")
+      assertEquals(Rules.turn(gameState(a(0)), direction(a(1))), gameState(c("expected")))
+    }
+  }
+
+  cases("m03-advance").foreach { c =>
+    test(s"advance: ${c("name").str}") {
+      assertEquals(Rules.advance(gameState(c("args")(0))), gameState(c("expected")))
+    }
+  }