* feat(backend): add created_at/updated_at to clients and maintain on create/update
backfill existing clients and set updated_at on mutations
* feat(frontend): carry created_at/updated_at in client models and round-trip via JSON
* feat(frontend): display Created and Updated columns in client table with proper date formatting
* i18n: add pages.inbounds.createdAt/updatedAt across all locales
* Update inbound.go
Remove duplicate code