[aeddi]

Summary

tmkms yubihsm keys import crashed when a priv_validator key file held a secp256k1 key —
with -t json, or with no -t when the file is named priv_validator_key.json, since both
take the same path. The file parses fine, since PrivValidatorKey accepts both key types, and
the command then reached an unreachable!() and exited 101 with "entered unreachable
code". It now exits with an error that names the file and says an Ed25519 consensus key is
required — the same wording the softsign provider uses when it loads such a file as a
consensus key (FORK.md entry 10).

Changes

• Refuse a secp256k1 key with an error instead of panicking — 2e7d379
• Test it through the real CLI, with a valid secp256k1 key file as the fixture — 2e7d379, b2d5ca0, fd0b80b
• Update the verification counts in FORK.md — 72e33ca
• Build both import tests' arguments in one place — 4537133

Testing

• Before the fix, the new test failed through the CLI with exit 101 and "entered unreachable
  code". After, it exits 1, and the error names the file and asks for an Ed25519 key.
• The fixture is a consistent secp256k1 key file: its public key and address are derived from
  the secret. Parsing accepts any key that can be a consensus key, and secp256k1 can, so the
  command reaches the branch under test.
• The existing Ed25519 import test still passes.
• 64 unit + 24 integration tests pass; cargo clippy --all-features is clean.