Add CBOR and agent initiated WebSocket connections (#51, #490, #646, #845, etc)

- Add version exchange between hub and agent.
- Introduce ConnectionManager for managing WebSocket and SSH connections.
- Implement fingerprint generation and storage in agent.
- Create expiry map package to store universal tokens.
- Update config.yml configuration to include tokens.
- Enhance system management with new methods for handling system states and alerts.
- Update front-end components to support token / fingerprint management features.
- Introduce utility functions for token generation and hub URL retrieval.

Co-authored-by: nhas <jordanatararimu@gmail.com>

beszel/internal/entities/container/container.go

@@ -34,10 +34,16 @@ type ApiStats struct {
 	MemoryStats MemoryStats `json:"memory_stats"`
 }
 
-func (s *ApiStats) CalculateCpuPercentLinux(prevCpuUsage [2]uint64) float64 {
-	cpuDelta := s.CPUStats.CPUUsage.TotalUsage - prevCpuUsage[0]
-	systemDelta := s.CPUStats.SystemUsage - prevCpuUsage[1]
-	return float64(cpuDelta) / float64(systemDelta) * 100
+func (s *ApiStats) CalculateCpuPercentLinux(prevCpuContainer uint64, prevCpuSystem uint64) float64 {
+	cpuDelta := s.CPUStats.CPUUsage.TotalUsage - prevCpuContainer
+	systemDelta := s.CPUStats.SystemUsage - prevCpuSystem
+
+	// Avoid division by zero and handle first run case
+	if systemDelta == 0 || prevCpuContainer == 0 {
+		return 0.0
+	}
+
+	return float64(cpuDelta) / float64(systemDelta) * 100.0
 }
 
 // from: https://github.com/docker/cli/blob/master/cli/command/container/stats_helpers.go#L185
@@ -99,12 +105,14 @@ type prevNetStats struct {
 
 // Docker container stats
 type Stats struct {
-	Name        string       `json:"n"`
-	Cpu         float64      `json:"c"`
-	Mem         float64      `json:"m"`
-	NetworkSent float64      `json:"ns"`
-	NetworkRecv float64      `json:"nr"`
-	PrevCpu     [2]uint64    `json:"-"`
-	PrevNet     prevNetStats `json:"-"`
-	PrevRead    time.Time    `json:"-"`
+	Name        string  `json:"n" cbor:"0,keyasint"`
+	Cpu         float64 `json:"c" cbor:"1,keyasint"`
+	Mem         float64 `json:"m" cbor:"2,keyasint"`
+	NetworkSent float64 `json:"ns" cbor:"3,keyasint"`
+	NetworkRecv float64 `json:"nr" cbor:"4,keyasint"`
+	// PrevCpu     [2]uint64    `json:"-"`
+	CpuSystem    uint64       `json:"-"`
+	CpuContainer uint64       `json:"-"`
+	PrevNet      prevNetStats `json:"-"`
+	PrevReadTime time.Time    `json:"-"`
 }