feat(assets): seven asset commands + Run dispatch/helpers

check-dupes, clean-dupes, check-mdl, fix-mdl, convert, upscale, compile
behind a single runner indirection, mirroring internal/depot's Run shape.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/assets/checkmdl.go

@@ -0,0 +1,67 @@
+package assets
+
+import (
+	"flag"
+	"fmt"
+	"io"
+
+	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/assets/mdl"
+)
+
+// mdlExt is the file set shared by the mdl commands.
+var mdlExt = map[string]bool{".mdl": true}
+
+// runCheckMDL reports uncompiled ASCII .mdl files and model-name mismatches.
+// Read-only. Exit exitFail if any problem is found.
+func runCheckMDL(args []string, stdout, stderr io.Writer) int {
+	fs := flag.NewFlagSet("check-mdl", flag.ContinueOnError)
+	fs.SetOutput(stderr)
+	nonRecursive := fs.Bool("non-recursive", false, "do not descend into subdirectories")
+	if err := fs.Parse(args); err != nil {
+		return exitUsage
+	}
+	paths := fs.Args()
+	if len(paths) == 0 {
+		fmt.Fprintln(stderr, "assets check-mdl: usage: check-mdl <path>...")
+		return exitUsage
+	}
+
+	files, err := walk(paths, mdlExt, !*nonRecursive)
+	if err != nil {
+		fmt.Fprintln(stderr, "assets check-mdl:", err)
+		return exitUsage
+	}
+
+	fail := false
+	for _, f := range files {
+		ascii, err := mdl.IsASCII(f)
+		if err != nil {
+			fmt.Fprintln(stderr, "assets check-mdl:", err)
+			return exitTool
+		}
+		if ascii {
+			fmt.Fprintf(stderr, "uncompiled ascii mdl: %s\n", f)
+			fail = true
+		}
+		mismatches, err := mdl.CheckNames(f)
+		if err != nil {
+			fmt.Fprintln(stderr, "assets check-mdl:", err)
+			return exitTool
+		}
+		expected := mdl.ExpectedName(f)
+		for _, m := range mismatches {
+			if m.Line == 0 {
+				fmt.Fprintf(stderr, "%s: mdl model-name mismatch: root node is %s, expected %s\n", f, m.Got, expected)
+			} else {
+				fmt.Fprintf(stderr, "%s: mdl model-name mismatch: line %d: %s is %s, expected %s\n", f, m.Line, m.What, m.Got, expected)
+			}
+			fail = true
+		}
+	}
+	if fail {
+		fmt.Fprintln(stderr, "check-mdl: found broken or uncompiled .mdl file(s)")
+		return exitFail
+	}
+	fmt.Fprintln(stdout, "check-mdl: OK")
+	return exitOK
+}