feat(cli): ludic build --check / ludicc --check - check without building

The parse, the types and the module rules (export, uses, layers, ports,
registries) run and nothing is emitted or linked: about three seconds
on Maroon Lake. In this mode the checker asks vis_check at each
reference it resolves, with a global's initializer and a registry's
entries seen from the files the emitter would use. Reseed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

COMPILING.md

@@ -350,6 +350,7 @@ The self-hosted `ludicc`/`ludic` (built with `bin/ludic-dev build-cli`) accept:
   --windowed         force a windowed (Cocoa) build
   --headless         force a headless build (stdin input, out.ppm output)
   --emit-llvm        stop at LLVM IR — write it and exit, no clang
+  --check            parse and check only (types, modules, uses, layers, ports); write nothing
   --fmt              lex + parse only; exit 0 if it parses, 1 on a parse error
                      (the check-docs gate; canonical formatting not yet restored)
   --save-temps       keep the intermediate .ll