docs: regenerate integration docs from staging-synced apps/sim

After merging staging, regenerated so the integration pages reflect current
source: correct block colors/configs (e.g. Gmail #FFFFFF), the new integrations
(sendblue, millionverifier, neverbounce, zerobounce), and staging's icon set.
Pages for integrations staging hid are removed; manual-content intros preserved.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ouiliame