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

tools/test/golden/macro/postfix_catch_method.expanded.json

@@ -0,0 +1,13 @@
+{"kind":"Program","statements":[
+  {"kind":"BoxDeclaration","name":"Worker","methods":{
+    "run": {"kind":"FunctionDeclaration","name":"run","params":[],"body":[{"kind":"Return","value":{"kind":"Literal","value":{"type":"int","value":0}}}],"static":false,"override":false}
+  }},
+  {"kind":"FunctionDeclaration","name":"main","params":["args"],"body":[
+    {"kind":"Local","variables":["w"],"inits":[{"kind":"New","class":"Worker","args":[]}]},
+    {"kind":"TryCatch",
+      "try":[{"kind":"MethodCall","object":{"kind":"Variable","name":"w"},"method":"run","arguments":[]}],
+      "catch":[{"type":"Error","var":"e","body":[{"kind":"Print","expression":{"kind":"Variable","name":"e"}}]}],
+      "cleanup":null}
+  ]}
+]}
+