Slack re-escapes HTML entities in the interaction payload
(< -> <, > -> >, & -> &), inflating the section text
past the 3000-char Block Kit limit when the button handler
rebuilds updated_blocks for chat.update.
The send path already budget-truncates, but the click handlers
used the echoed original_text verbatim. Cap it to 3000 chars
in both _handle_approval_action and _handle_slash_confirm_action.
Fixes#53693
liuhao1024
c13af09177