Fixed critical bug where my_public_key was not being generated when auto-adding
to config file. The issue had multiple root causes:
1. Buffer size bug: HEXKEY_LEN constant was too small (64) for public key (needs 129)
2. Silent failure in bytes_to_hex() when buffer too small
3. Wrong validation length checks causing incorrect need_* detection
4. Keypair regeneration instead of deriving public key from private key
5. Node ID conditional logic bug inserting it only when private key was invalid
Changes:
- Added PRIV_HEXKEY_LEN (65) and PUB_HEXKEY_LEN (129) constants
- Added is_valid_priv_key() and is_valid_pub_key() with correct length checks
- Added sc_compute_public_key_from_private() to derive public key when possible
- Fixed node_id insertion logic to check need_node_id instead of need_priv_key
- Updated bytes_to_hex() to null-terminate on error
Tested with real config file - public key now correctly generates as 128 hex chars.
Evgeny
b737b718cf