fix(ci): revert to per-dep pip download loop with --pre

Single pip-download call fails because the second fallback branch
(without --platform) tries to resolve Windows-only deps like winsdk
on Linux, where no wheels exist. The original per-dep loop isolates
each failure so the platform-specific branch handles each dep
independently. Add --pre throughout for winsdk (1.0.0bNN beta).

build-dist-windows.sh

@@ -69,20 +69,18 @@ VIS_DEPS=(
 
 ALL_DEPS=("${CORE_DEPS[@]}" "${WIN_DEPS[@]}" "${VIS_DEPS[@]}")
 
-# Reuse wheels from a previous cached run — only download if cache is empty
-if [ -d "$WHEEL_DIR" ] && [ -n "$(ls -A "$WHEEL_DIR" 2>/dev/null)" ]; then
-    echo "Using cached wheels from $WHEEL_DIR"
-else
-    # Single pip-download call — pip resolves all deps together, much faster than a loop.
-    # --pre is required because winsdk only ships beta wheels (1.0.0bNN).
-    pip download --pre --quiet --dest "$WHEEL_DIR" \
+# Per-dep loop with --pre (winsdk only ships beta wheels, e.g. 1.0.0b10).
+# Single-call resolution fails when one Windows-only dep can't resolve in
+# the Linux fallback branch, so we resolve each dep independently.
+for dep in "${ALL_DEPS[@]}"; do
+    pip download --pre --quiet --no-cache-dir --dest "$WHEEL_DIR" \
         --platform win_amd64 --python-version "${PYTHON_SHORT}" \
         --implementation cp --only-binary :all: \
-        "${ALL_DEPS[@]}" 2>/dev/null || \
-    pip download --pre --quiet --dest "$WHEEL_DIR" \
+        "$dep" 2>/dev/null || \
+    pip download --pre --quiet --no-cache-dir --dest "$WHEEL_DIR" \
         --only-binary :all: \
-        "${ALL_DEPS[@]}"
-fi
+        "$dep"
+done
 
 # Remove numpy 2.x wheels pulled as transitive deps (soundcard requires <2.0)
 for f in "$WHEEL_DIR"/numpy-2*; do