Note

Low Risk
Low risk: changes only Slack notification block construction to avoid per-section length errors, though it could slightly alter message formatting/truncation for very long lines.

Overview
Fixes Slack Block Kit section length violations by introducing splitIntoSectionBlocks, which splits long message text into multiple section blocks at newline boundaries and hard-truncates any single line that exceeds the per-section character limit.

buildContentBlocks now uses this splitter for both plain-string content and titled SlackMessageSection content, reducing the chance of Slack rejecting oversized section blocks.

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