fix: handleMerge must use return value of updateSupportStats

updateSupportStats returns a new SupportInfoV2 object — the original is
not mutated. The old code discarded the return value and persisted the
empty original, causing merge+contextLabel to always write empty
support_info ({global_strength:0.5, total_observations:0, slices:[]}).

Author: LvPengfei1

src/smart-extractor.ts

@@ -627,8 +627,8 @@ export class SmartExtractor {
       if (updatedEntry) {
         const meta = parseSmartMetadata(updatedEntry.metadata, updatedEntry);
         const supportInfo = parseSupportInfo(meta.support_info);
-        updateSupportStats(supportInfo, contextLabel, "support");
-        const finalMetadata = stringifySmartMetadata({ ...meta, support_info: supportInfo });
+        const updated = updateSupportStats(supportInfo, contextLabel, "support");
+        const finalMetadata = stringifySmartMetadata({ ...meta, support_info: updated });
         await this.store.update(matchId, { metadata: finalMetadata }, scopeFilter);
       }
     } catch {