Restore separate cmake --build calls for llama-server and
llama-quantize on both setup.sh and setup.ps1. The combined
approach made llama-quantize failure fatal, but it was originally
best-effort (|| true on Linux, [WARN] on Windows). The timing
savings from combining was only ~2.7s, not worth the semantic
change.
The Ninja + arch detection speedups are preserved (55s vs 1m 37s).
Build llama-server and llama-quantize in a single cmake --build
invocation on Windows, matching the same optimization done in
setup.sh. This allows MSBuild to better parallelize the two targets.
The Visual Studio generator is kept as-is (not switching to Ninja on
Windows since VS generator is the standard approach and interacts
with MSBuild).
