json(vm): fix birth dispatch; unify constructor naming (Box.birth/N); JsonNode factories return JsonNodeInstance; quick: enable heavy JSON with probe; builder: NYASH_BUILDER_DEBUG_LIMIT guard; json_query_min(core) harness; docs/tasks updated

apps/lib/json_native/lexer/scanner.nyash

@@ -24,6 +24,15 @@ box JsonScanner {
         me.line = 1
         me.column = 1
     }
+
+    // Runtime-safe initializer (bypass constructor arg loss on some VM paths)
+    reset_text(input_text) {
+        me.text = input_text
+        me.position = 0
+        me.length = input_text.length()
+        me.line = 1
+        me.column = 1
+    }
     
     // ===== 基本読み取りメソッド =====
     
@@ -233,6 +242,10 @@ box JsonScanner {
         // 整数部分
         if me.current() == "0" {
             me.advance()
+            // 先頭0の直後に数字が続くのは無効（例: 01）
+            if me.is_digit_char(me.current()) {
+                return null
+            }
         } else {
             if me.is_digit_char(me.current()) {
                 loop(not me.is_eof() and me.is_digit_char(me.current())) {
@@ -312,7 +325,10 @@ box JsonScanner {
                             i = i + 1
                         }
                     } else {
-                        // 通常のエスケープ
+                        // 通常のエスケープ（\" \\ \/ \b \f \n \r \t のみ）
+                        if not (escaped == "\"" or escaped == "\\" or escaped == "/" or escaped == "b" or escaped == "f" or escaped == "n" or escaped == "r" or escaped == "t") {
+                            return null
+                        }
                         me.advance()
                     }
                 } else {

apps/lib/json_native/lexer/tokenizer.nyash

@@ -15,7 +15,8 @@ box JsonTokenizer {
     birth(input_text) {
         // Avoid static module wrapper to ensure constructor args are preserved on VM path
         // (create_scanner(...) lost the argument under VM fallback in some cases)
-        me.scanner = new JsonScanner(input_text)
+        me.scanner = new JsonScanner("")
+        me.scanner.reset_text(input_text)
         me.tokens = new ArrayBox()
         me.errors = new ArrayBox()
     }
@@ -60,6 +61,14 @@ box JsonTokenizer {
         
         return me.tokens
     }
+
+    // Explicitly set input text (guards against constructor-arg loss)
+    set_input(input_text) {
+        if me.scanner == null {
+            me.scanner = new JsonScanner("")
+        }
+        me.scanner.reset_text(input_text)
+    }
     
     // 次のトークンを1つ取得
     next_token() {