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/linkedin-ads.js

@@ -11,6 +11,7 @@ if (!TOKEN) {
 async function api(method, path, body) {
   const headers = {
     'Authorization': `Bearer ${TOKEN}`,
+    'X-RestLi-Protocol-Version': '2.0.0',
     'Content-Type': 'application/json',
   }
   if (args['dry-run']) {