Add status command, deployment infrastructure, and fix proto paths

Rename proto/gen directories from mc-proxy to mc_proxy for valid protobuf
package naming. Add CLI status subcommand for querying running instance
health via gRPC. Add systemd backup service/timer and backup pruning
script. Add buf.yaml and proto-lint Makefile target. Add shutdown_timeout
config field.

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

internal/grpcserver/grpcserver.go

@@ -16,7 +16,7 @@ import (
 	"google.golang.org/grpc/status"
 	"google.golang.org/protobuf/types/known/timestamppb"
 
-	pb "git.wntrmute.dev/kyle/mc-proxy/gen/mc-proxy/v1"
+	pb "git.wntrmute.dev/kyle/mc-proxy/gen/mc_proxy/v1"
 	"git.wntrmute.dev/kyle/mc-proxy/internal/config"
 	"git.wntrmute.dev/kyle/mc-proxy/internal/db"
 	"git.wntrmute.dev/kyle/mc-proxy/internal/server"
@@ -24,7 +24,7 @@ import (
 
 // AdminServer implements the ProxyAdmin gRPC service.
 type AdminServer struct {
-	pb.UnimplementedProxyAdminServer
+	pb.UnimplementedProxyAdminServiceServer
 	srv    *server.Server
 	store  *db.Store
 	logger *slog.Logger
@@ -63,7 +63,7 @@ func New(cfg config.GRPC, srv *server.Server, store *db.Store, logger *slog.Logg
 		store:  store,
 		logger: logger,
 	}
-	pb.RegisterProxyAdminServer(grpcServer, admin)
+	pb.RegisterProxyAdminServiceServer(grpcServer, admin)
 
 	ln, err := net.Listen("tcp", cfg.Addr)
 	if err != nil {