fix: skip config.json network call when loading from local directory (#340)

[aarushisingh04]

fixes #340 : _from_pretrained with a local directory path no longer makes unnecessary network calls.

fix

• guard config.json download with if not os.path.isdir(model_id) so local loading makes zero network calls
• use caller's model_id and pass through all download parameters (force_download, revision, cache_dir, etc.) consistently
• default force_download to False to respect HF cache (matches HF ecosystem convention)

before

# always runs, even for local paths, crashes offline
_ = hf_hub_download(
    repo_id="google/timesfm-2.5-200m-pytorch",  # hardcoded
    filename="config.json",
    force_download=True,  # hardcoded
)

after

# only download config.json when loading from HF Hub
if not os.path.isdir(model_id):
    _ = hf_hub_download(
        repo_id=model_id,
        filename="config.json",
        force_download=force_download,
        # ... all other params passed through
    )