Phase 4b: enum types name magic-int value spaces

enum Name { A, B, C } declares named int constants; Enum.Variant is a
compile-time int (index by declaration order), usable in match patterns,
comparisons, setreg. New: parse_enum + dispatch, enum_ordinal resolver
(emit_core), Enum.Variant handling (emit_expr). Scoped to a naming layer over
int (no enum-typed variables), so register/save semantics are untouched.

combat.ludic battle menus dispatch on KnightAct/MageAct instead of 0..3;
chronorift golden byte-identical. Editor vocab (ludic_syntax.h, JetBrains,
TextMate, emacs) gained enum, dropped retired edge/export/pure decl keywords;
check-vocabulary + test-tools 28/0. when/if kept by choice; bitwise stays
functions. Reseeded, fixpoint holds, test.sh 14/14.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

selfhost/ast.ludic

@@ -15,6 +15,7 @@ const N_SYS:    int = 9
 const N_ARCH:   int = 10
 const N_EXTERN: int = 11
 const N_UI:     int = 12
+const N_ENUM:   int = 27         # enum Name { A, B, ... } — named int constants
 # statements
 const S_LET:      int = 10
 const S_ASSIGN:   int = 11