feat: implement real-time updates and enhance monitoring system

- Add structured logging with slog throughout application
- Implement real-time updates using Server-Sent Events and HTMX
- Add broadcaster system for instant UI updates when agents report stats
- Replace meta refresh with HTMX-powered seamless updates
- Add new API endpoints for HTMX fragments and SSE events
- Update templates to use HTMX for instant data refresh
- Enhance README with real-time features and updated documentation
- Remove obsolete template generation file

internal/api/api.go

@@ -4,12 +4,57 @@ import (
 	"encoding/json"
 	"log/slog"
 	"net/http"
+	"sync"
 
 	"github.com/go-chi/chi/v5"
 	"nerd-monitor/internal/stats"
 	"nerd-monitor/internal/store"
 )
 
+// Broadcaster manages Server-Sent Events clients.
+type Broadcaster struct {
+	clients map[chan string]bool
+	mu      sync.RWMutex
+}
+
+var apiBroadcaster = &Broadcaster{
+	clients: make(map[chan string]bool),
+}
+
+// Broadcast sends a message to all connected SSE clients.
+func (b *Broadcaster) Broadcast(message string) {
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+
+	for clientChan := range b.clients {
+		select {
+		case clientChan <- message:
+		default:
+			// Client channel is full, skip
+		}
+	}
+}
+
+// AddClient adds a new SSE client.
+func (b *Broadcaster) AddClient(clientChan chan string) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	b.clients[clientChan] = true
+}
+
+// RemoveClient removes an SSE client.
+func (b *Broadcaster) RemoveClient(clientChan chan string) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	delete(b.clients, clientChan)
+	close(clientChan)
+}
+
+// GetAPIBroadcaster returns the API broadcaster instance.
+func GetAPIBroadcaster() *Broadcaster {
+	return apiBroadcaster
+}
+
 // Handler manages HTTP requests.
 type Handler struct {
 	store *store.Store
@@ -40,6 +85,12 @@ func (h *Handler) ReportStats(w http.ResponseWriter, r *http.Request) {
 
 	slog.Debug("Updating agent stats", "agentID", agentID, "hostname", stat.Hostname, "cpu", stat.CPUUsage)
 	h.store.UpdateAgent(agentID, &stat)
+
+	// Broadcast update to all connected SSE clients
+	message := "event: stats-update\ndata: {\"type\": \"stats-update\", \"agentId\": \"" + agentID + "\"}\n\n"
+	slog.Info("Broadcasting stats update", "agentID", agentID)
+	apiBroadcaster.Broadcast(message)
+
 	w.Header().Set("Content-Type", "application/json")
 	json.NewEncoder(w).Encode(map[string]string{"status": "ok"})
 	slog.Debug("Stats report processed successfully", "agentID", agentID)