fix: correct remaining 5 API issues from codex review

- meta-ads: use empty array for special_ad_categories (not ['NONE'])
- ahrefs: add --target validation to all 5 site-explorer commands
- wistia: read SRT file contents from disk for captions create
- tiktok-ads: use URLSearchParams for cleaner URL construction
- mixpanel: require --from-date/--to-date for retention, add --event filter for export

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tools/clis/meta-ads.js

@@ -93,7 +93,7 @@ async function main() {
             name: args.name,
             objective: args.objective,
             status: args.status || 'PAUSED',
-            special_ad_categories: ['NONE'],
+            special_ad_categories: [],
           }
           result = await api('POST', `/act_${accountId}/campaigns`, body)
           break