fix(genesis): require a 32-byte validator public key in the schema

[JspIIV]

Closes: #413

Summary

Same shape as #359, one field over: the genesis schema for ValidatorManager accepts a validator publicKey of any even hex length, while the chain only accepts 32 bytes.

publicKey: schemaHex,   // any 0x + even number of hex digits

ValidatorRegistry.registerValidator enforces the real rule:

require(publicKey.length == ED25519_PUBLIC_KEY_LENGTH, InvalidPublicKeyFormat());

and the alloc builder knows it too — but only as a throw new Error('Public key must be 32 bytes') inside buildValidatorManagerGenesisAllocs, after schemaGenesisConfig.parse has already accepted the config (genesis.ts:161 parses, :188 builds). So a 31-byte key passes validation, passes the uniqueness check, and then fails later with a message that carries no path to the offending entry.

Change

• publicKey: schemaBytes32 — the schema already exists in types.ts and is exactly {32} bytes.
• Drop the now-unreachable runtime throw; the builder re-parses the schema on entry, so nothing gets past it.

The error moves to where the other genesis invariants live, with a path (validators.0.publicKey) instead of a bare string.

Tests

tests/unit/validator-manager-genesis-validation.test.ts: a 31-byte and a 33-byte key are rejected at the schema with the path set, a 32-byte key is accepted. Both rejections fail on main (the schema accepts them; only the builder would object). Run with mocha -r ts-node/register directly, since forge is not available here and the hardhat-foundry plugin refuses to start without it; make genesis was not run for the same reason. Every key in assets/*/genesis.config.ts is already 64 hex characters, so no shipped config changes behaviour.

Does not overlap #374, which normalizes hex casing and leaves the field type alone.

Related: #346, #359