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/smoke/pyvm/argv_inject_smoke.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+root=$(cd "$(dirname "$0")"/../../../.. && pwd)
+bin="$root/target/release/nyash"
+prog="$root/apps/tests/pyvm/argv_echo.nyash"
+
+out=$(NYASH_VM_USE_PY=1 "$bin" --backend vm "$prog" -- hello 2>/dev/null)
+test "$out" = "hello" || { echo "[FAIL] pyvm argv inject expected 'hello', got '$out'" >&2; exit 2; }
+echo "[OK] pyvm argv inject"
+