feat: field-move Drop (partial/nested/ptr), stmt/pat macros, Windows runtime

Sessions 70–74: partialMovedPaths + ptrAliases in bootstrap/selfhost CBE,
remaining drops after field moves, macro stmt/pat fragments, runtime_win.c
and MinGW hello CI, examples + drop-move smoke coverage, QUALITY_PLAN update.

tools/smoke_windows_hello.sh

@@ -0,0 +1,68 @@
+#!/usr/bin/env bash
+# Session 71 — Windows / MinGW hello smoke (also testable on Unix via BUX_RUNTIME=win).
+# Builds examples/hello.bux with the minimal runtime and checks stdout.
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+export BUX_STDLIB="${BUX_STDLIB:-$ROOT/lib}"
+unset BUX_DEBUG_FILE || true
+
+# Prefer buxc.exe on Windows, else buxc
+if [[ -x "$ROOT/buxc.exe" ]]; then
+  BUXC="$ROOT/buxc.exe"
+elif [[ -x "$ROOT/buxc" ]]; then
+  BUXC="$ROOT/buxc"
+else
+  (cd "$ROOT" && make build)
+  if [[ -x "$ROOT/buxc.exe" ]]; then BUXC="$ROOT/buxc.exe"
+  else BUXC="$ROOT/buxc"
+  fi
+fi
+
+# Force minimal runtime when not already on Windows (Linux/macOS local check)
+case "$(uname -s 2>/dev/null || echo unknown)" in
+  MINGW*|MSYS*|CYGWIN*|Windows_NT) ;;
+  *)
+    export BUX_RUNTIME="${BUX_RUNTIME:-win}"
+    ;;
+esac
+
+if ! command -v gcc >/dev/null 2>&1 && ! command -v cc >/dev/null 2>&1; then
+  echo "error: need gcc/cc on PATH (MinGW on Windows)" >&2
+  exit 1
+fi
+
+TMP=$(mktemp -d)
+trap 'rm -rf "$TMP"' EXIT
+mkdir -p "$TMP/src"
+cp -a "$ROOT/rt" "$TMP/"
+cat > "$TMP/bux.toml" <<'EOF'
+[Package]
+Name    = "hello"
+Version = "0.1.0"
+Type    = "bin"
+
+[Build]
+Output = "Bin"
+EOF
+cp "$ROOT/examples/hello.bux" "$TMP/src/Main.bux"
+
+echo "=== smoke_windows_hello: build+run ==="
+out=$("$BUXC" run "$TMP" 2>&1) || {
+  echo "$out" >&2
+  exit 1
+}
+echo "$out"
+echo "$out" | grep -q 'Hello, Bux!'
+
+# Confirm minimal runtime was used when forced / on Windows
+if [[ -f "$TMP/build/runtime.c" ]]; then
+  if ! grep -q 'Windows / MinGW minimal' "$TMP/build/runtime.c"; then
+    # On native Windows the CLI always copies runtime_win.c content into runtime.c
+    if grep -q 'pthread\|openssl/evp' "$TMP/build/runtime.c"; then
+      echo "error: expected runtime_win.c content, found full POSIX runtime" >&2
+      exit 1
+    fi
+  fi
+fi
+
+echo "PASS: smoke_windows_hello"