pyvm: split op handlers into ops_core/ops_box/ops_ctrl; add ops_flow + intrinsic; delegate vm.py without behavior change

net-plugin: modularize constants (consts.rs) and sockets (sockets.rs); remove legacy commented socket code; fix unused imports
mir: move instruction unit tests to tests/mir_instruction_unit.rs (file lean-up); no semantic changes
runner/pyvm: ensure using pre-strip; misc docs updates

Build: cargo build ok; legacy cfg warnings remain as before

src/mir/builder/exprs.rs

@@ -241,6 +241,7 @@ impl super::MirBuilder {
             ASTNode::Include { filename, .. } => self.build_include_expression(filename.clone()),
 
             ASTNode::Program { statements, .. } => self.cf_block(statements.clone()),
+            ASTNode::ScopeBox { body, .. } => self.cf_block(body.clone()),
 
             ASTNode::Print { expression, .. } => self.build_print_statement(*expression.clone()),