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/tests/parser_expr_postfix_catch.rs

@@ -0,0 +1,46 @@
+use crate::parser::NyashParser;
+
+fn enable_stage3() {
+    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+}
+
+#[test]
+fn expr_postfix_catch_basic() {
+    enable_stage3();
+    let src = r#"
+function main(args) {
+  f(1) catch(e) { print(e) }
+}
+"#;
+    let ast = NyashParser::parse_from_string(src).expect("parse ok");
+    fn has_try(ast: &crate::ast::ASTNode) -> bool {
+        match ast {
+            crate::ast::ASTNode::TryCatch { .. } => true,
+            crate::ast::ASTNode::Program { statements, .. } => statements.iter().any(has_try),
+            crate::ast::ASTNode::FunctionDeclaration { body, .. } => body.iter().any(has_try),
+            _ => false,
+        }
+    }
+    assert!(has_try(&ast), "expected TryCatch from expr‑postfix catch");
+}
+
+#[test]
+fn expr_postfix_catch_on_method_chain() {
+    enable_stage3();
+    let src = r#"
+function main(args) {
+  obj.m1().m2() catch { print("x") }
+}
+"#;
+    let ast = NyashParser::parse_from_string(src).expect("parse ok");
+    fn has_try(ast: &crate::ast::ASTNode) -> bool {
+        match ast {
+            crate::ast::ASTNode::TryCatch { .. } => true,
+            crate::ast::ASTNode::Program { statements, .. } => statements.iter().any(has_try),
+            crate::ast::ASTNode::FunctionDeclaration { body, .. } => body.iter().any(has_try),
+            _ => false,
+        }
+    }
+    assert!(has_try(&ast), "expected TryCatch wrapping method chain");
+}
+