feat: add verbose logging and log-level selection (#1941)

examples/cli/README.md

@@ -6,6 +6,11 @@ For detailed command-line arguments, run:
 ./bin/sd-cli -h
 ```
 
+Logging defaults to `info`. Use `--log-level <level>` to select `debug`, `verbose`,
+`info`, `warn`, or `error` (from most to least detailed). Each level includes
+messages at that level and all less detailed levels. `-v` and `--verbose` are
+equivalent to `--log-level verbose`. If repeated, the last logging option wins.
+
 For direct image repair or automatic post-generation YOLOv8 detection followed by cropped inpainting, see
 [ADetailer](../../docs/adetailer.md).