[emme1t]

Fixes #1324.

Loading a local model directory ending in / currently produces an empty registry name and raises ValueError. Normalize the path used for model-class lookup in both auto loaders, including checkpoint-parent lookup, while forwarding the original path to the selected model constructor.

The earlier #1591 included path normalization; it was closed in favor of #1594, which updated four reranker registry keys. The trailing-separator failure remains on current master. This patch covers that remaining path case.

Validation on Windows / Python 3.12 / Torch 2.15.0 CPU / Transformers 5.22.1:

• Offline regression tests save tiny local Bert embedding and reranking models, then compare actual inference for normal/checkpoint paths with single and repeated slash/native separators.
• Original source: 16 failed, 4 passed. Fixed regression plus existing import and Trainer compatibility tests: 29 passed.
• Changed-file Ruff checks, new-test formatting, compilation, dependency consistency and wheel build pass.

Full pretrained-model/GPU tests were not run.