Add `CLAUDE.md` and update `README.md` (#234) #598

Job	Run time
Check Formatting	25s
Check for Unneeded Dependencies	24s
Build and Cache Polkadot Binaries on macos-14	9s
Build and Cache Polkadot Binaries on ubuntu-24.04	7s
Check Clippy Lints	2m 22s
Unit Tests (ubuntu-24.04)	3m 42s
Unit Tests (macos-14)	6m 24s
	13m 33s

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