Document webhook Handlebars helpers

[thebiglabasky]

Summary

• document the shipped Checkly Handlebars helper surface on the webhook page
• add the exact tagValue syntax and behavior for key:value and key=value tags
• correct the random-number range and replace the stale Moment.js implementation wording
• remove links to the archived checkly/handlebars repository and point the legacy snippets page to the canonical webhook reference

Why

The public webhook docs delegated the full helper reference to an archived repository and did not document the keyed-tag helper shipped for ENG-28. Customers therefore had no durable public source for the syntax used to route webhook alerts by tag metadata.

Impact

Customers can now discover, copy, and test the supported helper syntax directly from the webhook documentation. The page also reflects the current runtime behavior instead of the archived implementation.

Validation

• pnpm --filter @checkly/handlebars test — 6,296 passed, 2 skipped
• npx mint broken-links
• python3 .github/scripts/check_frontmatter.py
• python3 .github/scripts/check_redirect_destinations.py
• npm run generate-sitemap — no sitemap diff
• git diff --check

[mintlify]

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Project	Status	Preview	Updated (UTC)
checkly-422f444a	🟢 Ready	View Preview	Jul 24, 2026, 2:29 PM