Trendz docs 1.15.2.1

Documents the Trendz Analytics 1.15.2.1 patch release (Jun 24, 2026) and updates
the related version metadata, plus a small simplification of the upgrade-instructions
heading logic.

Changes

Release notes

• src/content/_includes/docs/trendz/releases/v1-15-x.mdx — add the v1.15.2.1 (Jun 24, 2026) section:
  • Improvements: severity-based sorting for anomaly alarms; export for anomaly view;
    sorting and improved pagination for the task-executions list.
  • Bug fixes: two-factor authentication; "business entity not found" for customers
    viewing tenant-built views; prediction model fit; line-chart tooltip rendering;
    group-by amount for local dates; anomaly score sending for edge cases.

Version / release metadata

• src/data/versions.ts — bump TRENDZ_VER to 1.15.2.1.
• src/models/trendz-releases-table.ts — set the 1.15 family latestPatch to
  v1.15.2.1 / Jun 24 2026 and add the v1.15.2.1 patch row.
• src/models/trendz-upgrade-instructions.ts — add 1.15.2.1 to
  TRENDZ_UPGRADE_VERSIONS (LTS patch of 1.15.2, new upgrade mechanism, no HAProxy note).

Upgrade-instructions heading simplification

• src/components/upgrade-instructions/TrendzUpgradeSteps.astro
• src/pages/docs/trendz/installation/upgrade-instructions/[platform]/[familySlug].astro
  — always render Upgrading Trendz Analytics to {displayVersion}, dropping the
  latest {baseVersion} ({displayVersion}) variant for patch releases.

Testing

• pnpm check
• pnpm build:fast
• pnpm lint:linkcheck