Initial implementation of arca, a LUKS volume manager.

Go CLI using cobra with mount, unmount, status, and init subcommands.
Unlocks via udisks2 D-Bus (passphrase/keyfile) or cryptsetup (FIDO2/TPM2)
with ordered method fallback. Includes NixOS-specific LD_LIBRARY_PATH
injection for systemd cryptsetup token plugins.

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

vendor/github.com/spf13/cobra/MAINTAINERS

@@ -0,0 +1,13 @@
+maintainers:
+- spf13
+- johnSchnake
+- jpmcb
+- marckhouzam
+inactive:
+- anthonyfok
+- bep
+- bogem
+- broady
+- eparis
+- jharshman
+- wfernandes