fix: correct API issues found by codex review across 10 CLIs

Fixes found by automated codex review of all 47 CLI tools:

- resend: webhook field name endpoint_url -> endpoint
- mailchimp: change from Bearer to Basic auth per API docs
- kit: fail fast when api_secret required but not set
- activecampaign: automation add-contact needs --contact-id not --email
- google-ads: budget updateMask must be snake_case (amount_micros)
- meta-ads: special_ad_categories default to ['NONE'] not empty array
- linkedin-ads: add required X-RestLi-Protocol-Version header
- onesignal: auth prefix should be Key, not Basic
- mixpanel: query dates must be YYYY-MM-DD, not relative strings
- wistia: change from Bearer to Basic auth per API docs

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

tools/clis/mixpanel.js

@@ -155,8 +155,8 @@ async function main() {
             params: {
               events: [{ event: args.event || 'all' }],
               time_range: {
-                from_date: args['from-date'] || '30daysAgo',
-                to_date: args['to-date'] || 'today',
+                from_date: args['from-date'] || new Date(Date.now() - 30 * 86400000).toISOString().slice(0, 10),
+                to_date: args['to-date'] || new Date().toISOString().slice(0, 10),
               },
             },
           }