[Studio] Harden mock service data handling

[Aias00]

Summary

• return copied mock rows from cluster, instance, dashboard, connection, topic, message, consumer, ACL, and ops services
• keep mock topic search trimmed and blank-search safe
• make mock audit search null-safe while returning copied audit records
• consolidate related mock service hardening PRs into one review unit

Supersedes

#606 #607 #608 #609 #616 #617 #621 #622 #623 #604 #598

Tests

• npm ci --ignore-scripts --no-audit --no-fund
• npm test -- --run src/services/clusterService.test.ts src/services/instanceService.test.ts src/services/dashboardService.test.ts src/services/connectionsService.test.ts src/services/topicService.test.ts src/services/messageService.test.ts src/services/consumerService.test.ts src/services/aclService.test.ts src/services/opsService.test.ts
• npm run lint -- --max-warnings=999
• git diff --check

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