Scope mapping writes and stabilize sibling lookup

The tracker-mapping worker loaded a pattern in its claim transaction and
committed the resolution in a separate, later transaction. A full-row
Update would write back stale values and clobber any user edit made in
between. Add UpdateMapping, which writes only the worker-resolved
columns (common_tracker_pattern_id, third_party_id, and a description
filled only when still empty), leaving user-editable fields untouched.

Also add ORDER BY tracker_pattern_id to the sibling pattern lookup: the
query used LIMIT without an ORDER BY, so an over-limit match set
returned an arbitrary subset and could resolve the third party
differently across runs.

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

pkg/coredata/detected_tracker.go

@@ -271,6 +271,7 @@ WHERE cookie_banner_id = @cookie_banner_id
   AND initiator_domain = ANY(@domains)
   AND tracker_pattern_id IS NOT NULL
   AND tracker_pattern_id != @exclude_pattern_id
+ORDER BY tracker_pattern_id
 LIMIT @limit;
 `