fix(classify): treat .tgz as .tar.gz, not as meta asset

.tgz is a legitimate archive format (used by ollama darwin releases).
Remove it from the meta-asset filter and add a .tgz → .tar.gz mapping
in detectFormat.

cmd/classify/main.go

@@ -1249,7 +1249,6 @@ func isMetaAsset(name string) bool {
 		".sbom", ".spdx", ".json.sig", ".sigstore",
 		"_src.tar.gz", "_src.tar.xz", "_src.zip",
 		".d.ts",  // TypeScript definitions
-		".tgz",   // npm packages (not binary distributables)
 		".pub",   // cosign/SSH public keys
 	} {
 		if strings.HasSuffix(lower, suffix) {
@@ -1285,6 +1284,10 @@ func detectFormat(name string) string {
 			return ext
 		}
 	}
+	// .tgz is a common alias for .tar.gz (used by ollama, npm, etc.)
+	if strings.HasSuffix(lower, ".tgz") {
+		return ".tar.gz"
+	}
 	ext := filepath.Ext(lower)
 	return ext // includes leading dot, or "" if none
 }