improve packaging metadata, improve module hierarchy

ChangeLog.md

LICENSE

README.md

Setup.hs

app/Main.hs

flake.nix

src/Lib.hs

src/Tahoe/CHK.hs

src/Tahoe/CHK/Capability.hs

src/Tahoe/CHK/Crypto.hs

src/Tahoe/CHK/Merkle.hs

src/Tahoe/CHK/Netstring.hs

src/Tahoe/CHK/Types.hs

src/Tahoe/CHK/URIExtension.hs

src/Tahoe/CHK/Upload.hs

src/Tahoe/CHK/Util.hs

src/Tahoe/CHK/ZFEC.hs

tahoe-chk.cabal

test/NullServer.hs

test/SpecCHK.hs