Initial commit: Nerd Monitor - Cross-platform system monitoring application

Features:
- Multi-platform agents (Linux, macOS, Windows - AMD64 & ARM64)
- Real-time CPU, RAM, and disk usage monitoring
- Responsive web dashboard with live status indicators
- Session-based authentication with secure credentials
- Stale agent detection and removal (6+ months inactive)
- Auto-refresh dashboard (5 second intervals)
- 15-second agent reporting intervals
- Auto-generated agent IDs from hostnames
- In-memory storage (zero database setup)
- Minimal dependencies (Chi router + Templ templating)

Project Structure:
- cmd/: Agent and Server executables
- internal/: API, Auth, Stats, Storage, and UI packages
- views/: Templ templates for dashboard UI
- Makefile: Build automation for all platforms

Ready for deployment with comprehensive documentation:
- README.md: Full project documentation
- QUICKSTART.md: Getting started guide
- AGENTS.md: Development guidelines

internal/store/store.go

@@ -0,0 +1,78 @@
+package store
+
+import (
+	"sync"
+	"time"
+
+	"nerd-monitor/internal/stats"
+)
+
+// AgentStats represents the latest stats for an agent.
+type AgentStats struct {
+	ID        string
+	Hostname  string
+	CPUUsage  float64
+	RAMUsage  uint64
+	RAMTotal  uint64
+	DiskUsage uint64
+	DiskTotal uint64
+	LastSeen  time.Time
+}
+
+// Store manages agent statistics in memory.
+type Store struct {
+	mu     sync.RWMutex
+	agents map[string]*AgentStats
+}
+
+// New creates a new store.
+func New() *Store {
+	return &Store{
+		agents: make(map[string]*AgentStats),
+	}
+}
+
+// UpdateAgent updates or creates agent stats.
+func (s *Store) UpdateAgent(id string, stat *stats.Stats) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.agents[id] = &AgentStats{
+		ID:        id,
+		Hostname:  stat.Hostname,
+		CPUUsage:  stat.CPUUsage,
+		RAMUsage:  stat.RAMUsage,
+		RAMTotal:  stat.RAMTotal,
+		DiskUsage: stat.DiskUsage,
+		DiskTotal: stat.DiskTotal,
+		LastSeen:  time.Now(),
+	}
+}
+
+// GetAgent retrieves agent stats by ID.
+func (s *Store) GetAgent(id string) *AgentStats {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	return s.agents[id]
+}
+
+// GetAllAgents returns all agents.
+func (s *Store) GetAllAgents() []*AgentStats {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	agents := make([]*AgentStats, 0, len(s.agents))
+	for _, agent := range s.agents {
+		agents = append(agents, agent)
+	}
+	return agents
+}
+
+// DeleteAgent removes an agent.
+func (s *Store) DeleteAgent(id string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	delete(s.agents, id)
+}