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/sendgrid.js

@@ -56,6 +56,7 @@ async function main() {
 
   switch (cmd) {
     case 'send': {
+      if (!args.from || !args.to || !args.subject) { result = { error: '--from, --to, and --subject required' }; break }
       const body = {
         personalizations: [{
           to: args.to.split(',').map(e => ({ email: e.trim() })),
@@ -66,7 +67,7 @@ async function main() {
       if (args['template-id']) {
         body.template_id = args['template-id']
         if (args['template-data']) {
-          body.personalizations[0].dynamic_template_data = JSON.parse(args['template-data'])
+          try { body.personalizations[0].dynamic_template_data = JSON.parse(args['template-data']) } catch (e) { result = { error: 'Invalid JSON for --template-data: ' + e.message }; break }
         }
       } else {
         const content = []
@@ -117,6 +118,7 @@ async function main() {
           break
         }
         case 'get':
+          if (!rest[0]) { result = { error: 'Campaign ID required' }; break }
           result = await api('GET', `/marketing/campaigns/${rest[0]}`)
           break
         default:
@@ -172,6 +174,7 @@ async function main() {
     case 'validate':
       switch (sub) {
         case 'email': {
+          if (!args.email && !rest[0]) { result = { error: '--email required' }; break }
           const body = { email: args.email || rest[0] }
           result = await api('POST', '/validations/email', body)
           break