Add Quantus namespace with CAIP-2, CAIP-10 and CAIP-19 profiles

[n13]

This adds a quantus namespace for Quantus Network, a post-quantum secure Layer-1 blockchain.

Why a separate namespace

Quantus is built with the Polkadot SDK, but it is not interoperable with polkadot namespace tooling:

• Every extrinsic is signed with ML-DSA-87 or ML-DSA-65 (FIPS 204 / Dilithium). There is no sr25519, ed25519 or ECDSA support.
• Account IDs are the Poseidon hash of the ML-DSA public key, not the public key.
• Block hashes are Poseidon, not Blake2.
• Consensus is proof of work (QPoW). No relay chain, no XCM.

Using polkadot: would advertise compatibility that does not exist, for the same reason the hedera namespace declined to reuse eip155.

Files

• quantus/README.md (CAIP-104): ecosystem overview, network table, endpoints, references.
• quantus/caip2.md: name-based chain identifiers quantus:mainnet and quantus:planck, with a resolution method that maps each name to its genesis hash via chain_getBlockHash.
• quantus/caip10.md: SS58 addresses with prefix 189 (registered to Quantus in the SS58 registry). Addresses are always 49 characters starting with qz. Test cases include the raw account ID for each example address.
• quantus/caip19.md: native token as slip44:189189 (Quantus Network's registered SLIP-44 coin type).

The discussions-to headers point to this PR.