record module compile split in architecture docs

Author: mgomes

docs/architecture.md

@@ -76,6 +76,7 @@ Key files:
 - `vibes/modules.go` (module load + cache + compile flow)
 - `vibes/modules_paths.go` (module request parsing and path resolution helpers)
 - `vibes/modules_policy.go` (module allow/deny policy normalization and enforcement)
+- `vibes/modules_compile.go` (module compile/cache helpers and function-env cloning)
 - `vibes/modules_require.go` (runtime require execution, export/alias behavior, cycle reporting)
 
 ## Builtins