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

apps/tests/parser/semicolon_basic.nyash

@@ -0,0 +1,3 @@
+print("A"); print("B")
+return 0
+

apps/tests/parser/semicolon_else_edge.nyash

@@ -0,0 +1,8 @@
+function main(args) {
+  if 1 {
+    print("x")
+  } ; else {
+    print("y")
+  }
+}
+