feat(scanner): add debounced file watching with polling fallback

- Implement event queue with 3-second debouncing for file system events
- Add configurable polling fallback (default 3 min) via SCAN_POLL_INTERVAL_MINUTES
- Add SyncFilesystemWithDatabase to detect orphaned DB entries and new files
- Integrate utils.ResolveMediaURL for consistent media file path resolution
- Add COOKIE_SECURE env var with SameSite=LaxMode for session cookies
- Update media handler to properly decode URL paths for file serving
- Refactor scanner initialization to accept poll interval configuration

internal/handlers/dashboard.go

@@ -3,6 +3,7 @@ package handlers
 import (
 	"bookhoard/internal/database"
 	"bookhoard/internal/services"
+	"bookhoard/internal/utils"
 	"net/http"
 	"strconv"
 
@@ -151,7 +152,7 @@ func BuildSections(sections []services.DashboardSection) []SectionData {
 				MediaItemID:    itemUUID.String(),
 				Title:          item.Title,
 				Author:         textToString(item.Author),
-				CoverImagePath: textToString(item.CoverImagePath),
+				CoverImagePath: utils.ResolveMediaURL(item.LibraryID, item.CoverImagePath),
 			}
 		}