Add mcp logs command for streaming container logs

New server-streaming Logs RPC streams container output to the CLI.
Supports --tail/-n, --follow/-f, --timestamps/-t, --since.

Detects journald log driver and falls back to journalctl (podman logs
can't read journald outside the originating user session). New containers
default to k8s-file via mcp user's containers.conf.

Also adds stream auth interceptor for the agent gRPC server (required
for streaming RPCs).

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

internal/auth/auth.go

@@ -255,6 +255,52 @@ func AuthInterceptor(validator TokenValidator) grpc.UnaryServerInterceptor {
 	}
 }
 
+// StreamAuthInterceptor returns a gRPC stream server interceptor with
+// the same authentication rules as AuthInterceptor.
+func StreamAuthInterceptor(validator TokenValidator) grpc.StreamServerInterceptor {
+	return func(
+		srv any,
+		ss grpc.ServerStream,
+		info *grpc.StreamServerInfo,
+		handler grpc.StreamHandler,
+	) error {
+		md, ok := metadata.FromIncomingContext(ss.Context())
+		if !ok {
+			return status.Error(codes.Unauthenticated, "missing metadata")
+		}
+
+		authValues := md.Get("authorization")
+		if len(authValues) == 0 {
+			return status.Error(codes.Unauthenticated, "missing authorization header")
+		}
+
+		authHeader := authValues[0]
+		if !strings.HasPrefix(authHeader, "Bearer ") {
+			return status.Error(codes.Unauthenticated, "malformed authorization header")
+		}
+		token := strings.TrimPrefix(authHeader, "Bearer ")
+
+		tokenInfo, err := validator.ValidateToken(ss.Context(), token)
+		if err != nil {
+			slog.Error("token validation failed", "method", info.FullMethod, "error", err)
+			return status.Error(codes.Unauthenticated, "token validation failed")
+		}
+
+		if !tokenInfo.Valid {
+			return status.Error(codes.Unauthenticated, "invalid token")
+		}
+
+		if tokenInfo.HasRole("guest") {
+			slog.Warn("guest access denied", "method", info.FullMethod, "user", tokenInfo.Username)
+			return status.Error(codes.PermissionDenied, "guest access not permitted")
+		}
+
+		slog.Info("rpc", "method", info.FullMethod, "user", tokenInfo.Username, "account_type", tokenInfo.AccountType)
+
+		return handler(srv, ss)
+	}
+}
+
 // Login authenticates with MCIAS and returns a bearer token.
 func Login(serverURL, caCertPath, username, password string) (string, error) {
 	client, err := newHTTPClient(caCertPath)