feat: switch from deprecated mistralrs-server to mistralrs CLI

Build the mistralrs binary (CLI) instead of the deprecated
mistralrs-server. The RPM still installs as /usr/bin/mistralrs-server
for backwards compatibility. The systemd unit now invokes
`mistralrs-server serve` to use the CLI's serve subcommand.

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

rpm/mistralrs.spec

@@ -15,7 +15,7 @@ License:        MIT
 URL:            https://github.com/EricLBuehler/mistral.rs
 
 # Pre-built binary (produced in the build job, not rebuilt here)
-Source0:        mistralrs-server-%{mistralrs_flavour}
+Source0:        mistralrs-%{mistralrs_flavour}
 Source1:        mistralrs@.service
 Source2:        mistralrs@.conf.example
 
@@ -45,7 +45,7 @@ cp %{SOURCE2} .
 # Already built
 
 %install
-install -D -m 0755 mistralrs-server-%{mistralrs_flavour} \
+install -D -m 0755 mistralrs-%{mistralrs_flavour} \
     %{buildroot}%{_bindir}/mistralrs-server
 install -D -m 0644 mistralrs@.service \
     %{buildroot}%{_unitdir}/mistralrs@.service

rpm/systemd/mistralrs@.service

@@ -9,7 +9,7 @@ User=mistralrs
 Group=mistralrs
 SupplementaryGroups=video render
 EnvironmentFile=/etc/mistralrs/%i.conf
-ExecStart=@BINARY@ $MISTRALRS_ARGS
+ExecStart=@BINARY@ serve $MISTRALRS_ARGS
 Restart=on-failure
 RestartSec=10s