[Nari-Ab]

Closes #2200.

Replace deprecated torch_dtype load arguments with dtype in one sweep of Transformers model-loading calls and their kwargs dictionaries. Precision values and quantization decisions stay the same. Unsloth/Peft APIs, checkpoint config fields (including utils/kimi_k2.py) and unrelated utility files are unchanged.

Invert the existing floor-compatibility guard so it rejects the deprecated spelling. It covers direct calls, local dictionaries/updates/unpacks and locally selected AutoModel loader aliases, including the DPO path. Existing wrapper/CLI assertions follow the new spelling. Real tiny models saved locally exercise a CPU from_pretrained path and a meta-skeleton from_config path, with Python warnings and deprecated-dtype logging rejected; no model download is needed.

Validation on Python 3.11/macOS, main 7196345:

• Current Transformers 5.20.2: 716 passed, 18 skipped across the affected loader/trainer/CLI and guard tests, with forced color. Skips are 14 CUDA-only and 4 optional bitsandbytes cases.
• Actual Transformers 5.16.1 installed in an isolated temporary target: 92 passed across floor guards, dtype wrappers and the real local-model loads. Independently repeated by the parent with the same result. This uses installed Torch 2.14.1; it does not claim execution of the whole hosted pinned floor stack.
• Before production changes, 2 tests fail and 38 controls pass; a real from_config call fails on the exact deprecated dtype warning. Six independent mutations (direct kwarg, trainer dictionary, incremental dictionary, real config-load warning, direct scanner and dictionary scanner) are caught and restored.
• AST-equivalence verification covers all 29 changed source files after normalizing argument names and documentation; dtype expressions and algorithm behavior are preserved. Repo-wide Ruff, new-file formatting and whitespace checks pass. The changelog describes the removed warning.

Dependencies for verification were installed only in /private/tmp targets; the existing venv was not modified. Existing Typer/PEFT/TRL/pickle warnings remain, including three warnings in the focused floor run. No real GPU, native Linux/Windows or full-project local suite is claimed. The maintainer-controlled hosted floor/full CI remains required before merge.