refactor(editor): extract interop --validate-* into cli_validate_interop.cpp

Moves the four structural validators for INTEROP file formats
(--validate-stl, --validate-png, --validate-blp, --validate-jsondbc)
out of main.cpp into a new cli_validate_interop.{hpp,cpp} module.
These check files coming in/out of wowee from third-party tools,
distinct from cli_format_validate.cpp which validates the native
open formats (WOM, WOB, WOC, WHM).

main.cpp shrinks by 524 lines (10,644 to 10,121). Each validator
preserves its --json output mode for machine-readable reports.

tools/editor/cli_validate_interop.hpp

@@ -0,0 +1,25 @@
+#pragma once
+
+namespace wowee {
+namespace editor {
+namespace cli {
+
+// Dispatch the structural validators for INTEROP file formats —
+// the formats that flow into and out of wowee from third-party
+// tools, where the open-format validators in cli_format_validate
+// don't apply. Each does a deep structural check (chunks, CRCs,
+// magic numbers, schema constraints) beyond what --info-* shows.
+//   --validate-stl       ASCII STL (matches --export-stl output)
+//   --validate-png       PNG signature, chunks, CRCs
+//   --validate-blp       BLP1/BLP2 header + mip table bounds
+//   --validate-jsondbc   JSON DBC sidecar schema + record shape
+//
+// All four support an optional trailing `--json` flag for
+// machine-readable reports.
+//
+// Returns true if matched; outRc holds the exit code.
+bool handleValidateInterop(int& i, int argc, char** argv, int& outRc);
+
+} // namespace cli
+} // namespace editor
+} // namespace wowee