Phase 6a: rename core vocabulary (game/main/component/archetype/system)

game/module -> program, main -> entry, component -> property,
archetype -> model, system -> handler. Done via a transitional self-hosting
bootstrap: parser accepts both -> reseed -> compiler source moved to new
keywords + parser tightened to new-only -> reseed (fixpoint holds). Old keywords
now rejected.

Token-safe corpus migration (tools/ludic-tools/rename_kw.c) leaves the LLVM
@main/entry: labels in emit strings untouched; goldens byte-identical. Editor
vocab (header/JetBrains/TextMate/emacs), check-docs wrapper, and doc fences
updated; error string 'unknown component' -> 'unknown property'. test.sh 14/14,
test-tools 28/0, check-vocabulary green. (Doc prose pass to follow.)

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

tools/ludic-tools/ludic_syntax.h

@@ -52,8 +52,8 @@ typedef struct {
  * mirror the compiler's parser: anything parse_decl() dispatches on is a
  * declaration keyword, anything stmt() dispatches on is a statement keyword. */
 static const char* LUDIC_KW_DECL[] = {
-    "game","module","import","component","struct","archetype","enum","ui",
-    "const","var","fn","extern","system","main", 0
+    "program","import","property","struct","model","enum","ui",
+    "const","var","fn","extern","handler","entry", 0
 };
 static const char* LUDIC_KW_CLAUSE[] = {
     "phase","query","reads","writes", 0