The sshd handler performed a concrete type assertion on the accepted
connection, but the SSH listener's Accept() wraps each connection with
a traffic limiter (limitConn), obscuring the underlying *DirectForwardConn
type and causing 'sshd: wrong connection type' whenever a limiter was
configured.
Add an UnwrapConn() method to the traffic limiter wrapper and an
unwrapConn() helper in the handler that peels through wrapper layers
before the type switch. The handler uses the unwrapped conn only for
the type-specific DstAddr() call, while the original limiter-wrapped
conn drives data transfer so rate limiting remains effective.
Also track the last accept/bind error on service Status so callers can
retrieve the cause when a service enters the failed state.
- Default nil logger to Nop() in NewService to prevent panics
- Fix Events() returning 20-element slice padded with zero values
- Collect and join all errors in Close() instead of discarding
- Remove unnecessary variable shadow in execCmds
- Add doc comments to all 22 exported symbols
- Add 34 tests covering status, serve loop, close, and edge cases
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