builder/vm: stabilize json_lint_vm under unified calls

- Fix condition_fn resolution: Value call path + dev safety + stub injection
- VM bridge: handle Method::birth via BoxCall; ArrayBox push/get/length/set direct bridge
- Receiver safety: pin receiver in method_call_handlers to avoid undefined use across blocks
- Local vars: materialize on declaration (use init ValueId; void for uninit)
- Prefer legacy BoxCall for Array/Map/String/user boxes in emit_box_or_plugin_call (stability-first)
- Test runner: update LLVM hint to llvmlite harness (remove LLVM_SYS_180_PREFIX guidance)
- Docs/roadmap: update CURRENT_TASK with unified default-ON + guards

Note: NYASH_DEV_BIRTH_INJECT_BUILTINS=1 can re-enable builtin birth() injection during migration.

apps/lib/json_native/parser/parser.nyash

@@ -59,9 +59,14 @@ box JsonParser {
         // Step 2: 構文解析
         local result = me.parse_value()
         
-        // Step 3: 余剰トークンチェック
+        // Step 3: 余剰トークンチェック（詳細情報付き）
         if result != null and not me.is_at_end() {
-            me.add_error("Unexpected tokens after JSON value")
+            local extra = me.current_token()
+            if extra != null {
+                me.add_error("Unexpected tokens after JSON value: " + extra.get_type() + "(" + extra.get_value() + ")")
+            } else {
+                me.add_error("Unexpected tokens after JSON value")
+            }
             return null
         }