chore: move zola infrastructure to deprecated/

Relocate legacy static site generator configuration to clear
namespace for new Rust-based compiler:

- config.toml, netlify.toml
- sass/, templates/ directories
- themes/apollo submodule (updated .gitmodules path)

Content directory preserved at root for compatibility.

.gitmodules

@@ -1,5 +1,5 @@
 [submodule "themes/apollo"]
-	path = themes/apollo
+	path = deprecated/themes/apollo
 	url = https://github.com/not-matthias/apollo
 [submodule ".agent"]
 	path = .agent