update project structure

- move agent to /agent
- change /beszel to /src
- update workflows and docker builds

agent/utils.go

@@ -0,0 +1,15 @@
+package agent
+
+import "math"
+
+func bytesToMegabytes(b float64) float64 {
+	return twoDecimals(b / 1048576)
+}
+
+func bytesToGigabytes(b uint64) float64 {
+	return twoDecimals(float64(b) / 1073741824)
+}
+
+func twoDecimals(value float64) float64 {
+	return math.Round(value*100) / 100
+}