Trim activity display in slack automation

[gaspergrom]

Changes proposed ✍️

What

🤖 Generated by Copilot at bca407d

Improved Slack notification design for new activities by truncating long texts in newActivityBlocks.ts.
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🤖 Generated by Copilot at bca407d

truncate helps us
shorten long texts for Slack
autumn leaves fall fast

Why

How

🤖 Generated by Copilot at bca407d

• Add truncateText function to limit text length and append ellipsis (link)
• Use truncateText function to format text field of Slack message block for new activities (link)

Checklist ✅

• Label appropriately with Feature, Improvement, or Bug.
• Add screehshots to the PR description for relevant FE changes
• New backend functionality has been unit-tested.
• API documentation has been updated (if necessary) (see docs on API documentation).
• Quality standards are met.