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>