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/fixmdl.go

@@ -0,0 +1,103 @@
+package assets
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/assets/mdl"
+)
+
+// runFixMDL lowercases .mdl filenames and rewrites ASCII model identity to
+// match each file's stem. Binary models are skipped (the engine owns those).
+func runFixMDL(args []string, stdout, stderr io.Writer) int {
+	fs := flag.NewFlagSet("fix-mdl", flag.ContinueOnError)
+	fs.SetOutput(stderr)
+	dryRun := fs.Bool("dry-run", false, "report changes without touching disk")
+	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 fix-mdl: usage: fix-mdl [--dry-run] <path>...")
+		return exitUsage
+	}
+
+	files, err := walk(paths, mdlExt, !*nonRecursive)
+	if err != nil {
+		fmt.Fprintln(stderr, "assets fix-mdl:", err)
+		return exitUsage
+	}
+
+	changed := 0
+	failed := false
+	for _, f := range files {
+		// 1. Lowercase the basename if needed.
+		//
+		// ponytail: 35k files are each read once here (CheckNames + the rewrite
+		// on candidates). The shell reference batched an awk pass to avoid
+		// per-file subprocess spawns; in Go a plain read is cheap, so the batch
+		// is not worth porting. If profiling ever shows this hot, parallelize
+		// the loop.
+		lower := f
+		if base := filepath.Base(f); base != strings.ToLower(base) {
+			lower = filepath.Join(filepath.Dir(f), strings.ToLower(base))
+			if _, err := os.Stat(lower); err == nil {
+				fmt.Fprintf(stderr, "assets fix-mdl: lowercase collision: %s -> %s\n", f, lower)
+				failed = true
+				continue
+			}
+			if *dryRun {
+				fmt.Fprintf(stdout, "would lowercase: %s -> %s\n", f, lower)
+			} else {
+				if err := os.Rename(f, lower); err != nil {
+					fmt.Fprintf(stderr, "assets fix-mdl: failed to lowercase %s: %v\n", f, err)
+					failed = true
+					continue
+				}
+				fmt.Fprintf(stdout, "lowercased: %s -> %s\n", f, lower)
+			}
+			changed++
+		}
+
+		// 2. Rewrite model identity if the (lowercased) file has a mismatch.
+		//    In dry-run the on-disk file is still the original path.
+		readPath := lower
+		if *dryRun && lower != f {
+			readPath = f
+		}
+		data, err := os.ReadFile(readPath)
+		if err != nil {
+			fmt.Fprintln(stderr, "assets fix-mdl:", err)
+			failed = true
+			continue
+		}
+		out, wasChanged := mdl.FixNames(data, mdl.ExpectedName(lower))
+		if !wasChanged {
+			continue
+		}
+		if *dryRun {
+			fmt.Fprintf(stdout, "would fix: %s\n", lower)
+		} else {
+			if err := os.WriteFile(lower, out, 0o644); err != nil {
+				fmt.Fprintln(stderr, "assets fix-mdl:", err)
+				failed = true
+				continue
+			}
+			fmt.Fprintf(stdout, "fixed: %s\n", lower)
+		}
+		changed++
+	}
+
+	if changed == 0 {
+		fmt.Fprintln(stdout, "no broken mdl model names found")
+	}
+	if failed {
+		return exitFail
+	}
+	return exitOK
+}