feat(registry): remote-refresh Codex client model catalog (#4276)

Load codex_client_models.json like models.json with validation, revisioned
handler reloads, CI bake, and Home-aware updater gates so list IDs still
come from Home while templates can refresh on the edge.

cmd/validate_codex_models/main.go

@@ -0,0 +1,32 @@
+// Command validate_codex_models validates a Codex client model catalog file.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/router-for-me/CLIProxyAPI/v7/internal/registry"
+)
+
+func main() {
+	var inputPath string
+	flag.StringVar(&inputPath, "file", "", "Codex client model catalog JSON file")
+	flag.Parse()
+
+	if strings.TrimSpace(inputPath) == "" {
+		fmt.Fprintln(os.Stderr, "error: --file is required")
+		os.Exit(2)
+	}
+	data, err := os.ReadFile(inputPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: read %s: %v\n", inputPath, err)
+		os.Exit(1)
+	}
+	if err = registry.ValidateCodexClientModelsJSON(data); err != nil {
+		fmt.Fprintf(os.Stderr, "error: invalid Codex client model catalog %s: %v\n", inputPath, err)
+		os.Exit(1)
+	}
+	fmt.Printf("Validated Codex client model catalog: %s\n", inputPath)
+}