codewhale config set accepts typos and unknown keys silently; did-you-mean uses a stale key list

[Hmbown]

Found while designing settings-by-conversation. Observed on 0.10.0 in a throwaway home:

• codewhale config set calm_mode flase and codewhale config set totally_bogus_key 42 both exit 0 and write those values into config.toml. calm_mode lives in settings.toml, so nothing ever reads the write. config doctor still reports clean. The cause is the fallthrough into extras (crates/config/src/lib.rs ~2933).
• unknown_setting_message suggests keys from the hand-kept Settings::available_settings() (settings.rs ~1933) instead of SETTINGS_SCHEMA.

Fix

• Validate the key and value type against the declared schema.
• Refuse unknown keys with the nearest valid key from SETTINGS_SCHEMA.
• Route settings.toml keys to settings.toml.
• Make config doctor report keys that nothing reads.
• Keep an explicit --force escape hatch only if some real workflow needs it.