Polygon Ships Critical Heimdall Fixes, Sets Mandatory Zurich Hardfork

Polygon PoS shipped Bor v2.8.1/v2.8.2 and Heimdall v0.8.1/v0.8.2/v0.9.0, fixing security and liveness issues without mainnet disruption. Heimdall v0.9.0 Zurich hardfork is mandatory for all mainnet operators before block 47,880,000 (2026-06-25). Fixes include bounded GetWitnessMetadata requests, oversized-block prevention, and validator-only fee withdrawals.