feat(home): add direnv and enable nix-direnv #43

Job	Run time
check (x86_64-linux, ubuntu-24.04)	36s
check (aarch64-linux, ubuntu-24.04-arm)	36s
switch (aarch64-linux, ubuntu-24.04-arm)	2m 4s
switch (x86_64-linux, ubuntu-24.04)	2m 0s
	5m 16s

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