feat: macros (multi-rep, hygiene), Drop field-move, lean multi-OS CI

Sessions 56–69: declarative macro! with rep/zip/literal/block and
unhygienic var $name binders; partial field-move skip Drop; @[Release]
polish; LSP type hierarchy; CI Nim cache + lean macOS + Windows smoke.

tools/smoke_drop_move.sh

@@ -0,0 +1,81 @@
+#!/usr/bin/env bash
+# Golden-ish smoke: field-move + partial field-move Drop emission.
+# Ensures C for TakeItems has no Bag_Drop (would double-free returned Array).
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+BUXC="${BUXC:-$ROOT/buxc}"
+export BUX_STDLIB="${BUX_STDLIB:-$ROOT/lib}"
+unset BUX_DEBUG_FILE || true
+
+if [[ ! -x "$BUXC" ]]; then
+  (cd "$ROOT" && make build)
+fi
+
+TMP=$(mktemp -d)
+trap 'rm -rf "$TMP"' EXIT
+
+# --- move_field (whole local into field) ---
+echo "=== smoke: move_field ==="
+mkdir -p "$TMP/mf/src"
+cp -a "$ROOT/rt" "$TMP/mf/"
+cat > "$TMP/mf/bux.toml" <<'EOF'
+[Package]
+Name    = "move_field"
+Version = "0.1.0"
+Type    = "bin"
+
+[Build]
+Output = "Bin"
+EOF
+cp "$ROOT/examples/move_field.bux" "$TMP/mf/src/Main.bux"
+(cd "$TMP/mf" && "$BUXC" run .)
+# Only the MakeBox *body* (not prototypes / other functions)
+if sed -n '/^Box MakeBox(void) {/,/^}/p' "$TMP/mf/build/main.c" | grep -q 'Array_Drop\|Bag_Drop'; then
+  echo "error: MakeBox still drops moved Array" >&2
+  sed -n '/^Box MakeBox(void) {/,/^}/p' "$TMP/mf/build/main.c"
+  exit 1
+fi
+echo "  move_field: PASS (run + no Array_Drop of moved local)"
+
+# --- partial field move ---
+echo "=== smoke: move_field_partial ==="
+mkdir -p "$TMP/mp/src"
+cp -a "$ROOT/rt" "$TMP/mp/"
+cat > "$TMP/mp/bux.toml" <<'EOF'
+[Package]
+Name    = "move_field_partial"
+Version = "0.1.0"
+Type    = "bin"
+
+[Build]
+Output = "Bin"
+EOF
+cp "$ROOT/examples/move_field_partial.bux" "$TMP/mp/src/Main.bux"
+(cd "$TMP/mp" && "$BUXC" run .)
+# TakeItems must not call Bag_Drop after moving bag.items out
+if sed -n '/^Array_int TakeItems/,/^}/p' "$TMP/mp/build/main.c" | grep -q 'Bag_Drop'; then
+  echo "error: TakeItems still Bag_Drops after partial field move" >&2
+  sed -n '/^Array_int TakeItems/,/^}/p' "$TMP/mp/build/main.c"
+  exit 1
+fi
+echo "  move_field_partial: PASS (run + TakeItems has no Bag_Drop)"
+
+# --- early return Drop counts ---
+echo "=== smoke: drop_early_return ==="
+mkdir -p "$TMP/de/src"
+cp -a "$ROOT/rt" "$TMP/de/"
+cat > "$TMP/de/bux.toml" <<'EOF'
+[Package]
+Name    = "drop_early_return"
+Version = "0.1.0"
+Type    = "bin"
+
+[Build]
+Output = "Bin"
+EOF
+cp "$ROOT/examples/drop_early_return.bux" "$TMP/de/src/Main.bux"
+out=$(cd "$TMP/de" && "$BUXC" run .)
+echo "$out" | grep -q 'PASS'
+echo "  drop_early_return: PASS"
+
+echo "PASS: smoke_drop_move (field-move + partial + early-return)"