feat(arweave): ECDSA-only HD derivation (coin 472)

[gitctrlx]

Summary

• Add kobe-arweave: ECDSA-only offline HD (SLIP-44 472), path m/44'/472'/0'/0/{i}
• Address = Base64URL_nopad(SHA-256(compressed 33-byte secp256k1 pubkey)) — matches node ar_wallet (ECDSA_PUB_KEY_SIZE = 33) and arweave-js master-ec identifier hash
• Helpers: address_from_compressed_pubkey, owner_from_compressed_pubkey (recovered owner when tx owner is empty)
• CLI: kobe arweave / kobe ar (new / import)
• Umbrella feature arweave in all-chains (not mainstream)
• Wire CI thumb no_std + publish.yml crates.io order
• Workspace 3.4.0; rewrite CONTRIBUTING.md chain registration matrix (CI/publish rows explicit)
• Explicit non-goals: RSA wallets, transaction signing

Protocol

Item	Value
Curve	secp256k1
Pubkey	compressed 33 B
Address	Base64URL(SHA-256(pk)), 43 chars
Path	m/44'/472'/0'/0/{i}
KAT abandon@0	G3y00z9F3EvSzJprpIH6vPqHVZPH0rLqLrg0JOsd88Y
KAT abandon@1	s67JULQPjY6wpxYV4imfx_Ui6twtC_jfxnluJT4GOSo

Sources: ECDSA Keys, ar_wallet.erl, arweave-js origin/master-ec.

Test plan

• cargo test -p kobe-arweave (KATs + uncompressed negative)
• cargo test -p kobe --all-features --test cross_chain_smoke
• cargo test --workspace --all-features
• cargo deny check (advisories/bans/licenses/sources)
• host check-no-std includes kobe-arweave
• CLI: kobe arweave import -m "abandon…about" --json → KAT address
• CI green (lint / test / deny / no_std thumb)

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