Teku 26.6.1 Fixes Snappy Loading, Windows Support Dropped

Teku 26.6.1 released with bug fixes; optional for 26.6.0 users. Fixes snappy native library loading. 26.6.0 requires JDK 25, adds Gloas POST /eth/v1/beacon/states/{state_id}/builders endpoint, renames two execution payload REST endpoints. Windows support removed in next release.