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/macro/loopform/for_step2.nyash

@@ -0,0 +1,4 @@
+for(fn(){ local i = 0 }, i <= 4, fn(){ i = i + 2 }, fn(){
+  print(i)
+})
+

apps/tests/macro/loopform/foreach_empty.nyash

@@ -0,0 +1,5 @@
+local arr = []
+foreach(arr, "x", fn() {
+  print(x)
+})
+

apps/tests/macro/loopform/nested_block_break.nyash

@@ -0,0 +1,9 @@
+// Nested bare block containing break; should terminate loop when i==3
+local i = 0
+loop (i < 10) {
+  { if i == 3 { break } }
+  print(i)
+  i = i + 1
+}
+return 0
+

apps/tests/macro/loopform/nested_if_break.nyash

@@ -0,0 +1,11 @@
+local i = 0
+loop(1) {
+  if (i < 10) {
+    if (i == 3) {
+      break
+    }
+  }
+  print(i)
+  i = i + 1
+}
+

apps/tests/macro/loopform/nested_if_continue.nyash

@@ -0,0 +1,14 @@
+local i = 0
+loop(i < 6) {
+  if (i % 2 == 0) {
+    if (i == 4) {
+      i = i + 1
+      continue
+    }
+    i = i + 1
+    continue
+  }
+  print(i)
+  i = i + 1
+}
+