selfhost: Integrate ChatGPT's using system parser fixes

- Fix using paths in mini_vm_prints.nyash and mini_vm_core.nyash
- Convert multi-line JSON literal to single-line in empty args smoke test
- Remove extra closing brace in mini_vm_core.nyash
- Add verbose logging for using system visited file tracking

🤖 Generated with [Claude Code](https://claude.ai/code)

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

apps/selfhost/vm/boxes/mini_vm_core.nyash

@@ -745,4 +745,3 @@ static box MiniVm {
     return out
   }
 }
-}

apps/selfhost/vm/boxes/mini_vm_prints.nyash

@@ -1,8 +1,8 @@
-using selfhost.vm.scan as MiniVmScan
-using selfhost.vm.binop as MiniVmBinOp
-using selfhost.vm.compare as MiniVmCompare
+using selfhost.common.mini_vm_scan as MiniVmScan
+using selfhost.common.mini_vm_binop as MiniVmBinOp
+using selfhost.common.mini_vm_compare as MiniVmCompare
 // Use the JSON adapter facade for cursor ops (next_non_ws, digits)
-using selfhost.vm.json as MiniJsonLoader
+using selfhost.vm.boxes.json_cur as MiniJsonLoader
 
 static box MiniVmPrints {
   // dev trace flag (0=OFF)