feat(ui): engine.inspector page block, action, dataset, flow node, app nav and widget strings move into the studio namespace (#25922 slice S2)

520 keys per language leave app-shell's designer table for
@object-ui/i18n/namespaces/studio, text unchanged; app-shell's lookup
already asks the table first and the namespace second, so no call site
changes.

Claude-Session: https://claude.ai/code/session_01JQwxbX9LnJhjTQPJEmoBYi
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude