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/golang.org/x/sys/unix/endian_little.go

@@ -0,0 +1,9 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+//
+//go:build 386 || amd64 || amd64p32 || alpha || arm || arm64 || loong64 || mipsle || mips64le || mips64p32le || nios2 || ppc64le || riscv || riscv64 || sh
+
+package unix
+
+const isBigEndian = false