Implement SyncWarden v0.1.0

Full Syncthing tray wrapper with:
- System tray with 5 icon states (idle/syncing/paused/error/disconnected)
- Syncthing REST API client with auto-discovered API key
- Long-polling event listener for real-time status
- Transfer rate monitoring, folder tracking, recent files, conflict counting
- Full context menu with folders, recent files, settings toggles
- Embedded admin panel binary (webview, requires CGO)
- OS notifications via beeep (per-event configurable)
- Syncthing process management with auto-restart
- Cross-platform installer with autostart
- CI pipeline for Linux (.deb + .tar.gz) and Windows (.zip)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/syncthing/events.go

@@ -0,0 +1,83 @@
+package syncthing
+
+import (
+	"log"
+	"sync"
+	"time"
+)
+
+// EventHandler is called for each batch of new events.
+type EventHandler func(events []Event)
+
+// EventListener long-polls the Syncthing event API.
+type EventListener struct {
+	client  *Client
+	handler EventHandler
+	sinceID int
+	stopCh  chan struct{}
+	wg      sync.WaitGroup
+}
+
+// NewEventListener creates a new event listener.
+func NewEventListener(client *Client, sinceID int, handler EventHandler) *EventListener {
+	return &EventListener{
+		client:  client,
+		handler: handler,
+		sinceID: sinceID,
+		stopCh:  make(chan struct{}),
+	}
+}
+
+// Start begins long-polling in a goroutine.
+func (el *EventListener) Start() {
+	el.wg.Add(1)
+	go el.loop()
+}
+
+// Stop stops the event listener and waits for it to finish.
+func (el *EventListener) Stop() {
+	close(el.stopCh)
+	el.wg.Wait()
+}
+
+// LastEventID returns the last processed event ID.
+func (el *EventListener) LastEventID() int {
+	return el.sinceID
+}
+
+func (el *EventListener) loop() {
+	defer el.wg.Done()
+
+	backoff := time.Second
+	maxBackoff := 30 * time.Second
+
+	for {
+		select {
+		case <-el.stopCh:
+			return
+		default:
+		}
+
+		events, err := el.client.Events(el.sinceID, 30)
+		if err != nil {
+			log.Printf("event poll error: %v", err)
+			select {
+			case <-el.stopCh:
+				return
+			case <-time.After(backoff):
+			}
+			backoff *= 2
+			if backoff > maxBackoff {
+				backoff = maxBackoff
+			}
+			continue
+		}
+
+		backoff = time.Second
+
+		if len(events) > 0 {
+			el.sinceID = events[len(events)-1].ID
+			el.handler(events)
+		}
+	}
+}