refactor(rpm): install binary to /usr/bin instead of /opt

Install the binary as /usr/bin/mistralrs-server-<flavour> using the
standard %{_bindir} macro. The update-alternatives system manages
the /usr/bin/mistralrs-server symlink as before. Removes the
non-standard /opt/mistralrs/<flavour>/bin/ directory structure.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

rpm/mistralrs.spec

@@ -29,9 +29,6 @@ ExclusiveArch:  x86_64
 %global __requires_exclude ^lib(cuda|cudart|cudnn|cublas|cublasLt|curand|nvrtc|nccl)
 Requires:       systemd
 
-# Flavours are mutually exclusive with other flavours of themselves at the
-# same install path, but you can install cuda13, cuda13-fa, cuda13-fa-nccl
-# side by side — they all get separate /opt paths.
 Provides:       mistralrs-server = %{version}-%{release}
 
 %description
@@ -39,9 +36,9 @@ mistral.rs is a blazingly fast LLM inference engine written in Rust.
 This package provides the %{mistralrs_flavour} flavour, built with features:
 cuda, cudnn, and optionally flash-attn and nccl depending on flavour name.
 
-Binary installs to /opt/mistralrs/%{mistralrs_flavour}/bin/ and can coexist
-with other flavours. Use `update-alternatives --config mistralrs-server` to
-select the default /usr/bin/mistralrs-server symlink target.
+The binary installs to %{_bindir}/mistralrs-server-%{mistralrs_flavour}.
+Use `update-alternatives --config mistralrs-server` to select the default
+/usr/bin/mistralrs-server symlink target.
 
 %prep
 # Nothing to unpack; Source0 is the binary itself
@@ -54,14 +51,14 @@ cp %{SOURCE2} .
 
 %install
 install -D -m 0755 mistralrs-server-%{mistralrs_flavour} \
-    %{buildroot}/opt/mistralrs/%{mistralrs_flavour}/bin/mistralrs-server
+    %{buildroot}%{_bindir}/mistralrs-server-%{mistralrs_flavour}
 install -D -m 0644 mistralrs@.service \
     %{buildroot}%{_unitdir}/mistralrs-%{mistralrs_flavour}@.service
 install -D -m 0644 mistralrs@.conf.example \
     %{buildroot}%{_sysconfdir}/mistralrs/%{mistralrs_flavour}.conf.example
 
 # Patch the unit to point at this flavour's binary
-sed -i "s|@BINARY@|/opt/mistralrs/%{mistralrs_flavour}/bin/mistralrs-server|g" \
+sed -i "s|@BINARY@|%{_bindir}/mistralrs-server-%{mistralrs_flavour}|g" \
     %{buildroot}%{_unitdir}/mistralrs-%{mistralrs_flavour}@.service
 sed -i "s|@FLAVOUR@|%{mistralrs_flavour}|g" \
     %{buildroot}%{_unitdir}/mistralrs-%{mistralrs_flavour}@.service
@@ -77,7 +74,7 @@ case "%{mistralrs_flavour}" in
     *fa*)   priority=20 ;;
 esac
 update-alternatives --install /usr/bin/mistralrs-server mistralrs-server \
-    /opt/mistralrs/%{mistralrs_flavour}/bin/mistralrs-server "${priority}"
+    %{_bindir}/mistralrs-server-%{mistralrs_flavour} "${priority}"
 
 %systemd_post mistralrs-%{mistralrs_flavour}@.service
 
@@ -87,12 +84,12 @@ update-alternatives --install /usr/bin/mistralrs-server mistralrs-server \
 %postun
 if [ $1 -eq 0 ]; then
     update-alternatives --remove mistralrs-server \
-        /opt/mistralrs/%{mistralrs_flavour}/bin/mistralrs-server
+        %{_bindir}/mistralrs-server-%{mistralrs_flavour}
 fi
 %systemd_postun_with_restart mistralrs-%{mistralrs_flavour}@.service
 
 %files
-/opt/mistralrs/%{mistralrs_flavour}/
+%{_bindir}/mistralrs-server-%{mistralrs_flavour}
 %{_unitdir}/mistralrs-%{mistralrs_flavour}@.service
 %{_sysconfdir}/mistralrs/%{mistralrs_flavour}.conf.example