Drop altcoin pip extras, CI deps and docs; update CLAUDE.md and FORK.md

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

pyproject.toml

@@ -62,11 +62,3 @@ orjson = [
 uvloop = [
     "uvloop>=0.14",
 ]
-# For various altcoins
-blake256 = ["blake256>=0.1.1", ]
-crypto = ["pycryptodomex>=3.8.1", ]
-groestl = ["groestlcoin-hash>=1.0.1", ]
-tribushashm = ["tribushashm>=1.0.5", ]
-xevan-hash = ["xevan-hash", ]
-dash_hash = ["dash_hash>=1.4", ]
-zny-yespower-0-5 = ["zny-yespower-0-5", ]