feat(cli): deprecate validate, inspect, layout in favor of check

One stderr notice per invocation and _meta.deprecated: true in JSON mode
(shared helper next to withMeta; layout owns both inspect and layout via
createInspectCommand). Help descriptions gain the pointer. No behavior
change; removal ships separately once migration telemetry says usage
has decayed.

fix(producer): route info/debug logs to stderr — the compiler's
'Localized remote media' line was landing on stdout ahead of validate's
--json payload, breaking every piped consumer. Diagnostics now share
stderr with warn/error; render progress uses its own channel.

packages/cli/src/utils/updateCheck.ts

@@ -40,6 +40,8 @@ export interface UpdateMeta {
   version: string;
   latestVersion?: string;
   updateAvailable: boolean;
+  /** Present (and true) only for commands superseded by `check`; absent otherwise. */
+  deprecated?: boolean;
 }
 
 /**
@@ -130,9 +132,30 @@ export function getUpdateMeta(): UpdateMeta {
 /**
  * Wrap a JSON payload with the _meta version envelope.
  * Use this in all --json command outputs for consistent agent-friendly metadata.
+ *
+ * Pass `{ deprecated: true }` from a command superseded by `check` (validate,
+ * inspect, layout) to add `_meta.deprecated: true`; every other call site is
+ * unaffected — the key is only ever added, never set to `false`.
  */
-export function withMeta<T extends object>(data: T): T & { _meta: UpdateMeta } {
-  return { ...data, _meta: getUpdateMeta() };
+export function withMeta<T extends object>(
+  data: T,
+  options?: { deprecated?: boolean },
+): T & { _meta: UpdateMeta } {
+  const meta = getUpdateMeta();
+  if (options?.deprecated) meta.deprecated = true;
+  return { ...data, _meta: meta };
+}
+
+/**
+ * One-line deprecation notice for a command superseded by `check`. Always
+ * writes to stderr (never stdout), so a --json invocation's stdout stays
+ * pure, parseable JSON. Call once per invocation, before the command's own
+ * output.
+ */
+export function printDeprecationNotice(command: string): void {
+  process.stderr.write(
+    `'hyperframes ${command}' is deprecated and will be removed in a future release. Use 'hyperframes check' instead.\n`,
+  );
 }
 
 /**