system updater: complete overhaul

Move system update flow to GO, with a CLI (convenient AIO tool) and
server integration. All lifecycle, scheduling, execution occurs on
backend side.

Run some backends via pkexec, some via terminal like paru/yay.

Incorporate flatpak as an option to update.

Add terminal override setting in GUI, in addition to $TERMINAL env
variable.

fixes #2307
fixes #822
fixes #1102
fixes #1812
fixes #1087
fixes #1743

core/internal/server/sysupdate/handlers.go

@@ -0,0 +1,55 @@
+package sysupdate
+
+import (
+	"net"
+
+	"github.com/AvengeMedia/DankMaterialShell/core/internal/server/models"
+	"github.com/AvengeMedia/DankMaterialShell/core/internal/server/params"
+)
+
+func HandleRequest(conn net.Conn, req models.Request, m *Manager) {
+	switch req.Method {
+	case "sysupdate.getState":
+		models.Respond(conn, req.ID, m.GetState())
+	case "sysupdate.refresh":
+		force := params.BoolOpt(req.Params, "force", false)
+		m.Refresh(RefreshOptions{Force: force})
+		models.Respond(conn, req.ID, m.GetState())
+	case "sysupdate.upgrade":
+		handleUpgrade(conn, req, m)
+	case "sysupdate.cancel":
+		m.Cancel()
+		models.Respond(conn, req.ID, m.GetState())
+	case "sysupdate.acquire":
+		m.Acquire()
+		models.Respond(conn, req.ID, models.SuccessResult{Success: true})
+	case "sysupdate.release":
+		m.Release()
+		models.Respond(conn, req.ID, models.SuccessResult{Success: true})
+	case "sysupdate.setInterval":
+		seconds, err := params.Int(req.Params, "seconds")
+		if err != nil {
+			models.RespondError(conn, req.ID, err.Error())
+			return
+		}
+		m.SetInterval(seconds)
+		models.Respond(conn, req.ID, m.GetState())
+	default:
+		models.RespondError(conn, req.ID, "unknown method: "+req.Method)
+	}
+}
+
+func handleUpgrade(conn net.Conn, req models.Request, m *Manager) {
+	opts := UpgradeOptions{
+		IncludeFlatpak: params.BoolOpt(req.Params, "includeFlatpak", true),
+		IncludeAUR:     params.BoolOpt(req.Params, "includeAUR", true),
+		DryRun:         params.BoolOpt(req.Params, "dry", false),
+		CustomCommand:  params.StringOpt(req.Params, "customCommand", ""),
+		Terminal:       params.StringOpt(req.Params, "terminal", ""),
+	}
+	if err := m.Upgrade(opts); err != nil {
+		models.RespondError(conn, req.ID, err.Error())
+		return
+	}
+	models.Respond(conn, req.ID, m.GetState())
+}