[BUG] inverted else clause causes immediate failure.

[DFanso]

src/main.go

Lines 41-43 contain a fatal error that triggers when CLAUDE_API_KEY is set, which is the opposite of the intended behavior. This makes the Claude provider completely non-functional.

https://github.com/DFanso/commit-msg/pull/19#discussion_r2401744548

[DFanso]

in main.go