resolve_auto_classifier_timeout

Resolve the wall-clock budget for one Auto classifier decision batch.

Resolves models.auto_classifier_timeout through the standard env → config.toml → default precedence. An out-of-range value (below AUTO_CLASSIFIER_TIMEOUT_FLOOR or above AUTO_CLASSIFIER_TIMEOUT_CEILING) is discarded with a logged warning and the next lower-precedence layer is tried, so a bad higher-precedence override cannot mask a valid TOML setting (or the default) and can never remove the deadline that keeps a stalled classifier from hanging every gated tool call.