fix: scanner cur_path leak when directory enqueued (ASan)

build_asan/CMakeFiles/server.dir/link.txt

@@ -0,0 +1 @@
+/nix/store/788mx070y81zjlg5ipcl0cra3afviw9k-gcc-wrapper-15.2.0/bin/gcc -O3 -DNDEBUG -fsanitize=address -Wl,--dependency-file=CMakeFiles/server.dir/link.d CMakeFiles/server.dir/src/server/server.c.o CMakeFiles/server.dir/src/shared/array_list.c.o CMakeFiles/server.dir/src/shared/chunk.c.o CMakeFiles/server.dir/src/shared/compression.c.o CMakeFiles/server.dir/src/shared/config.c.o CMakeFiles/server.dir/src/shared/data.c.o CMakeFiles/server.dir/src/shared/delta.c.o CMakeFiles/server.dir/src/shared/file.c.o CMakeFiles/server.dir/src/shared/log.c.o CMakeFiles/server.dir/src/shared/metadata.c.o CMakeFiles/server.dir/src/shared/multiprocessing.c.o CMakeFiles/server.dir/src/shared/protocol.c.o CMakeFiles/server.dir/src/shared/queue.c.o CMakeFiles/server.dir/src/shared/transport_ssh.c.o CMakeFiles/server.dir/src/shared/transport_tcp.c.o CMakeFiles/server.dir/src/shared/transport_tls.c.o CMakeFiles/server.dir/src/shared/utils.c.o -o server  /nix/store/gd74vdpqzq0qmmikvmrf3r3kghhhnf50-zstd-1.5.7/lib/libzstd.so /nix/store/y18pnbvfarnilsmgayswvi1khaw9wbsc-openssl-3.6.2/lib/libssl.so /nix/store/y18pnbvfarnilsmgayswvi1khaw9wbsc-openssl-3.6.2/lib/libcrypto.so _deps/xxhash-build/libxxhash.a