feat(secrets)!: Replace sops with agenix-rekey

sops-nix is tending to be fairly complex for our use-cases, which adds
difficulty to deploying, maintaining our wrapper module, keeping
".env.bin" files, etc.

agenix-rekey is a lot simpler.

notable in this commit is the `// { outputPath = ...; }` hack in
flake.nix. This is needed due to snowfall-lib otherwise butchering paths
such that agenix-rekey is unable to show us what secrets exist with
`agenix edit`, etc... companion to that is the lib.snowfall.fs stuff in
the secrets/default.nix file

Change-Id: Id3e79cfc7d37a7b7de7b8cc42f7392c4d8bd07c5
Reviewed-on: https://git.clicks.codes/c/Infra/NixFiles/+/801
Reviewed-by: Skyler Grey <minion@clicks.codes>
Tested-by: Skyler Grey <minion@clicks.codes>
diff --git a/secrets/keys/minion/tiny-yubikey.pub b/secrets/keys/minion/tiny-yubikey.pub
new file mode 100644
index 0000000..0838d68
--- /dev/null
+++ b/secrets/keys/minion/tiny-yubikey.pub
@@ -0,0 +1,7 @@
+#       Serial: 23751432, Slot: 1
+#         Name: MINION_TINY_YUBIKEY
+#      Created: Sun, 21 Jul 2024 12:49:01 +0000
+#   PIN policy: Once   (A PIN is required once per session, if set)
+# Touch policy: Always (A physical touch is required for every decryption)
+#    Recipient: age1yubikey1qf92p7gj5k8pavnzrzg644plfqcpkc8laj2l4avdfnem2re08tuqsu7ynnf
+AGE-PLUGIN-YUBIKEY-1PP4K5QVZR6DHL7G8RVVJ0