Resolves durationSeconds from request/config values and validates provider bounds.
For string inputs, this keeps generation behavior: non-numeric strings are treated as "unset" rather than throwing.
Raw duration value from request or config.
Minimum allowed duration.
Maximum allowed duration.
Normalized duration in seconds.
Resolves durationSeconds from request/config values and validates provider bounds.
For string inputs, this keeps generation behavior: non-numeric strings are treated as "unset" rather than throwing.