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/godbus/dbus/v5/.golangci.yml

@@ -0,0 +1,13 @@
+version: "2"
+
+linters:
+  enable:
+    - unconvert
+    - unparam
+  exclusions:
+    presets:
+      - std-error-handling
+
+formatters:
+  enable:
+    - gofumpt