fix: add input validation and safe JSON parsing across 13 CLIs

Add missing parameter validation to prevent /path/undefined API calls:
- dub: require --url for links create
- google-search-console: require --sitemap-url for sitemaps submit
- kit: validate IDs and emails for subscribers, forms, sequences, tags, broadcasts
- mailchimp: validate IDs for lists get, campaigns get/create/send, members add, reports get
- resend: validate --from/--to/--subject for send, audience/contact IDs for contacts
- rewardful: validate IDs for affiliates get/update, commissions get, links create
- semrush: require --domain/--phrase for all domain and keyword commands
- sendgrid: validate --from/--to/--subject for send, campaign IDs, email for validate

Wrap bare JSON.parse() calls in try/catch for user-provided JSON:
- dub (--links), ga4 (--params), kit (--fields x4), mixpanel (--properties x2),
  onesignal (--filters), paddle (--scheduled-change, --items x2),
  resend (--emails, --variables x2), segment (--properties, --traits, --events),
  sendgrid (--template-data)

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

tools/clis/ga4.js

@@ -150,7 +150,14 @@ async function main() {
           if (!args['api-secret']) { result = { error: '--api-secret required' }; break }
           if (!args['client-id']) { result = { error: '--client-id required' }; break }
           if (!args['event-name']) { result = { error: '--event-name required' }; break }
-          const eventParams = args.params ? JSON.parse(args.params) : {}
+          let eventParams = {}
+          if (args.params) {
+            try {
+              eventParams = JSON.parse(args.params)
+            } catch {
+              result = { error: 'Invalid JSON in --params' }; break
+            }
+          }
           const body = {
             client_id: args['client-id'],
             events: [{