Add probo-agent CLI and deviceagent library

Introduce the standalone device agent binary and shared library
for enrollment, posture checks, self-update, and OS service
integration. Include build targets, module deps, and release
workflow so the agent can ship independently of server changes.

Signed-off-by: Bryan Frimin <bryan@probo.com>

pkg/deviceagent/checks/runcmd_paths_linux.go

@@ -0,0 +1,30 @@
+// Copyright (c) 2025-2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package checks
+
+var linuxCommandPaths = map[string][]string{
+	"firewall-cmd": {"/usr/bin/firewall-cmd"},
+	"gsettings":    {"/usr/bin/gsettings"},
+	"iptables":     {"/usr/sbin/iptables", "/sbin/iptables", "/usr/bin/iptables"},
+	"lsblk":        {"/usr/bin/lsblk", "/bin/lsblk"},
+	"nft":          {"/usr/sbin/nft", "/sbin/nft"},
+	"systemctl":    {"/usr/bin/systemctl", "/bin/systemctl"},
+	"timedatectl":  {"/usr/bin/timedatectl", "/bin/timedatectl"},
+	"ufw":          {"/usr/sbin/ufw", "/sbin/ufw"},
+}
+
+func commandCandidates(cmd string) []string {
+	return linuxCommandPaths[cmd]
+}