feat(proxmox): add journalctl streaming API endpoint for LXC containers

Add new /api/v1/proxmox/journalctl/:node/:vmid/:service endpoint that
streams real-time journalctl output from Proxmox LXC containers via
WebSocket connection. This enables live monitoring of container services
from the GoDoxy WebUI.

Implementation includes:
- New proxmox API handler with path parameter validation
- WebSocket upgrade for streaming output
- LXCCommand helper for executing commands over Proxmox VNC websocket
- LXCJournalctl wrapper for convenient journalctl -u service -f invocation
- Updated API documentation with proxmox integration

internal/api/v1/proxmox/journalctl.go

@@ -0,0 +1,65 @@
+package proxmoxapi
+
+import (
+	"io"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	"github.com/yusing/godoxy/internal/proxmox"
+	"github.com/yusing/goutils/apitypes"
+	"github.com/yusing/goutils/http/websocket"
+)
+
+type JournalctlRequest struct {
+	Node    string `uri:"node" binding:"required"`
+	VMID    int    `uri:"vmid" binding:"required"`
+	Service string `uri:"service" binding:"required"`
+}
+
+// @x-id				"journalctl"
+// @BasePath		/api/v1
+// @Summary		Get journalctl output
+// @Description	Get journalctl output
+// @Tags			proxmox,websocket
+// @Accept			json
+// @Produce		application/json
+// @Param			path		path		JournalctlRequest	true	"Request"
+// @Success		200			string		plain	"Journalctl output"
+// @Failure		400			{object}	apitypes.ErrorResponse	"Invalid request"
+// @Failure		403			{object}	apitypes.ErrorResponse	"Unauthorized"
+// @Failure		500			{object}	apitypes.ErrorResponse	"Internal server error"
+// @Router			/api/v1/proxmox/journalctl/{node}/{vmid}/{service} [get]
+func Journalctl(c *gin.Context) {
+	var request JournalctlRequest
+	if err := c.ShouldBindUri(&request); err != nil {
+		c.JSON(http.StatusBadRequest, apitypes.Error("invalid request", err))
+		return
+	}
+
+	node, ok := proxmox.Nodes.Get(request.Node)
+	if !ok {
+		c.JSON(http.StatusNotFound, apitypes.Error("node not found"))
+		return
+	}
+
+	manager, err := websocket.NewManagerWithUpgrade(c)
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to upgrade to websocket"))
+		return
+	}
+	defer manager.Close()
+
+	reader, err := node.LXCJournalctl(c.Request.Context(), request.VMID, request.Service)
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to get journalctl output"))
+		return
+	}
+	defer reader.Close()
+
+	writer := manager.NewWriter(websocket.TextMessage)
+	_, err = io.Copy(writer, reader)
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to copy journalctl output"))
+		return
+	}
+}