add resize method for buckets lanczos/bicubic

[PlagueKind]

Adds a resize_method field to DatasetConfig (default: lanczos) that
controls the PIL resample filter used for all image resize ops during
data loading. Previously hardcoded to BICUBIC everywhere.

• toolkit/basic.py: new get_resize_method() helper + RESIZE_METHODS map
• toolkit/config_modules.py: DatasetConfig.resize_method (default 'lanczos')
• toolkit/data_loader.py: ImageDataset / PairedImageDataset read resize_method
• toolkit/dataloader_mixins.py: all resize call sites use
  get_resize_method(self.dataset_config.resize_method)
• toolkit/control_generator.py: hardcoded to lanczos (no per-dataset
  config available at control-map generation time)
• UI: dataset card now exposes a Resize Method dropdown
  (ui/src/types.ts, jobConfig.ts, SimpleJob.tsx)

Backwards compatible — existing configs without resize_method default
to lanczos.