fix: manual host creation and improve host identification

- Add machine_id support for manual host creation from GUI
- Generate temporary 'pending-{uuid}' machine_id for new hosts
- Agent now collects and sends machine_id on every update
- Backend replaces pending machine_id with real one on first agent connection
- Remove unnecessary duplicate name check (friendly_name can be duplicated)
- Add get_machine_id() function to agent (reads from /etc/machine-id, /var/lib/dbus/machine-id, or generates fallback)
- Display IP address in Network tab on host details page
- Fix network tab visibility conditions to include host.ip

This ensures proper host identification using machine_id while maintaining backwards compatibility with API credentials as the primary authentication method.

backend/src/routes/hostRoutes.js

@@ -172,15 +172,6 @@ router.post(
 			// Generate unique API credentials for this host
 			const { apiId, apiKey } = generateApiCredentials();
 
-			// Check if host already exists
-			const existingHost = await prisma.hosts.findUnique({
-				where: { friendly_name: friendly_name },
-			});
-
-			if (existingHost) {
-				return res.status(409).json({ error: "Host already exists" });
-			}
-
 			// If hostGroupId is provided, verify the group exists
 			if (hostGroupId) {
 				const hostGroup = await prisma.host_groups.findUnique({
@@ -196,6 +187,7 @@ router.post(
 			const host = await prisma.hosts.create({
 				data: {
 					id: uuidv4(),
+					machine_id: `pending-${uuidv4()}`, // Temporary placeholder until agent connects with real machine_id
 					friendly_name: friendly_name,
 					os_type: "unknown", // Will be updated when agent connects
 					os_version: "unknown", // Will be updated when agent connects
@@ -321,6 +313,10 @@ router.post(
 			.optional()
 			.isArray()
 			.withMessage("Load average must be an array"),
+		body("machineId")
+			.optional()
+			.isString()
+			.withMessage("Machine ID must be a string"),
 	],
 	async (req, res) => {
 		try {
@@ -338,6 +334,11 @@ router.post(
 				updated_at: new Date(),
 			};
 
+			// Update machine_id if provided and current one is a placeholder
+			if (req.body.machineId && host.machine_id.startsWith("pending-")) {
+				updateData.machine_id = req.body.machineId;
+			}
+
 			// Basic system info
 			if (req.body.osType) updateData.os_type = req.body.osType;
 			if (req.body.osVersion) updateData.os_version = req.body.osVersion;