feat(cli): ludic deps - the module graph as the compiler resolved it

With LUDIC_DEPS=<file> the compiler records every reference the
visibility pass resolves (from module, to module) and every assignment
to another module's global. ludic deps prints the modules,
dependencies, largest cycle, cross writes and globals written from
outside, with --graph, --dot, --writes, --uses MOD, --check FILE and
--baseline FILE. Reseed.

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

selfhost/main.ludic

@@ -208,6 +208,7 @@ entry {
   check_duplicate_decls()
   check_program()                                 # L4: the types agree before anything is emitted
   emit_program()
+  deps_flush()                                    # LUDIC_DEPS=<file>: the module graph (ludic deps)
 
   # --emit-llvm, or no binary target: emit IR and stop (stdout when out is null).
   if emit_ir { ir_flush(out);  return }