fix: suppress legacy warnings in machine JSON paths

harness/tht/cli/schema_cmd.py

@@ -1,5 +1,6 @@
 # ruff: noqa: BLE001, S110, B008
 import logging
+import warnings
 from pathlib import Path
 from typing import TypedDict
 
@@ -143,10 +144,19 @@ def _schema_json(payload: dict) -> None:
 
 
 def _machine_config(config: Path):
-    try:
-        return load_config(config)
-    except ConfigError:
-        raise _MachineSchemaError("invalid_configuration") from None
+    # Legacy resource keys remain accepted, but their deprecation warning is not part of
+    # the JSON machine contract.  Keep this filter scoped to this call so human commands
+    # (and unrelated warnings/errors) retain their existing behavior.
+    with warnings.catch_warnings():
+        warnings.filterwarnings(
+            "ignore",
+            message=r"^DEPRECATION: legacy workspace resource keys are deprecated;",
+            category=FutureWarning,
+        )
+        try:
+            return load_config(config)
+        except ConfigError:
+            raise _MachineSchemaError("invalid_configuration") from None
 
 
 def _physical_or_error(cfg):