feat: broadcast progress updates from KOReader sync

Add WebSocket broadcast to KOReader progress sync:
- Integrate ConnectionManager into KOReaderHandler
- Broadcast progress updates on successful sync
- Include source device information (model, type)
- Real-time updates to all connected clients

When KOReader devices sync reading progress, all connected
WebSocket clients (web browsers, mobile apps, other devices)
receive instant updates.

internal/handlers/koreader.go

@@ -2,6 +2,7 @@ package handlers
 
 import (
 	"bookmann/internal/database"
+	wsync "bookmann/internal/sync"
 	"fmt"
 	"net/http"
 	"time"
@@ -12,11 +13,12 @@ import (
 )
 
 type KOReaderHandler struct {
-	db *database.Queries
+	db          *database.Queries
+	connManager *wsync.ConnectionManager
 }
 
-func NewKOReaderHandler(db *database.Queries) *KOReaderHandler {
-	return &KOReaderHandler{db: db}
+func NewKOReaderHandler(db *database.Queries, connManager *wsync.ConnectionManager) *KOReaderHandler {
+	return &KOReaderHandler{db: db, connManager: connManager}
 }
 
 type KOReaderProgressRequest struct {
@@ -274,6 +276,24 @@ func (h *KOReaderHandler) updateProgressForBook(c echo.Context, userID pgtype.UU
 		LastSyncSource:  pgtype.Text{String: "koreader", Valid: true},
 	})
 
+	if err == nil {
+		// Broadcast progress update to all connected WebSocket clients
+		deviceInfo := book.DeviceInfo
+		if deviceInfo.DeviceModel == "" {
+			deviceInfo.DeviceModel = "KOReader Device"
+		}
+
+		h.connManager.BroadcastProgressUpdate(
+			uuid.UUID(mediaItemID.Bytes),
+			book.Percentage,
+			wsync.SourceDevice{
+				ID:   uuid.UUID(userID.Bytes).String(),
+				Name: deviceInfo.DeviceModel,
+				Type: "koreader",
+			},
+		)
+	}
+
 	return err
 }