Track source on detected storage trackers

The cookie detector tags every detection with a source (script,
pre-existing, http) but the storage detector did not, so storage
rows always landed in detected_trackers with source NULL even though
the SDK already distinguishes wrapper writes from pre-load scans.

Plumb a "script"/"pre-existing" source from the storage detector
through the report endpoint into DetectedStorageItem, so the column
gets populated for localStorage, sessionStorage, indexedDB and
cacheStorage entries. No schema change is needed: detected_trackers
already accepts CookieSource values regardless of tracker_type, and
the existing row renders the badge as soon as it is non-null.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/cookiebanner/service.go

@@ -123,6 +123,7 @@ type (
 		Key          string
 		StorageType  coredata.TrackerType
 		ValueSize    *int
+		Source       *coredata.CookieSource
 		InitiatorURL *string
 	}
 
@@ -2124,6 +2125,7 @@ func (s *Service) ReportDetectedTrackers(
 						TrackerType:  ds.StorageType,
 						Identifier:   ds.Key,
 						ValueSize:    ds.ValueSize,
+						Source:       ds.Source,
 						InitiatorURL: ds.InitiatorURL,
 					},
 					&inserted,