Summary

• add a machine-readable telemetry contract for dashboard event names, allowed properties, allowed breakdowns, runtime events, and forbidden sensitive fields
• add PostHog tooling tests that fail when insights reference unregistered events, filter/break down on unsupported properties, or the runtime dashboard/API contract drifts
• remove an unused PostHog sync helper that blocked strict typechecking in the touched tool package

Verification

• PATH=/tmp/codex-node-v24/bin:$PATH npx nx test posthog-tools --runInBand
• PATH=/tmp/codex-node-v24/bin:$PATH npx tsc -p tools/posthog/tsconfig.json --noEmit
• PATH=/tmp/codex-node-v24/bin:$PATH npx nx lint posthog-tools
• PATH=/tmp/codex-node-v24/bin:$PATH npx nx test examples-chat-angular --runInBand