In fact, you *must* use mnemonic to successfully recover a modern node!
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Changed: JSON-RPC: `recover` takes a 12-word mnemonic for nodes created by v25.12 or later.
We cannot use the codex32 or raw hex for recovery of 25.12 nodes,
since they will then use the incorrect derivation for all paths, and
be unable to spend (or even find!) their funds.
So implement `getsecret` to replace `getcodexsecret`.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Changed: `lightning-hsmtool`: `getsecret` replaces `getcodexsecret` for modern nodes (gives mnemonic).
Changelog-Deprecated: `lightning-hsmtool`: `getcodexsecret`. Use `getsecret`.
When installed, the name is `lightning-hsmtool`. We actually copy
`tools/hsmtool` to `tools/lightning-hsmtool` but that's a silly step
which we should get rid of.
So:
1. Make sure our documentation always refers to it as lightning-hsmtool.
2. Make sure our tests invoke it as `lightning-hsmtool`.
3. Rename the C file.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
