BIDSLayout crashes with BIDSConflictingValuesError when zero-padded entities in filenames match integer entities in JSON sidecars #1255

Description

If a user specifies a zero-padded entity in their filename (e.g., run-01) but provides the standard integer equivalent in their JSON sidecar (e.g., "run": 1), BIDSLayout crashes entirely with a BIDSConflictingValuesError during indexing.

The Bug

When BIDSLayout checks for overlapping entities between the filename and the JSON sidecar, it uses a naive string comparison (src/bids/layout/index.py around line 520):

if str(md_val) != file_val:
    raise BIDSConflictingValuesError(...)

Because file_val is parsed as the string "01" directly from the filename, and md_val is parsed as the integer 1 from the JSON sidecar, the expression evaluates "1" != "01" as True. This raises a fatal exception that prevents the layout from initializing, even though the values are numerically identical.

Steps to Reproduce

1. Create a minimal dataset with a file named sub-01_task-rest_run-01_bold.nii.gz.
2. Add a JSON sidecar sub-01_task-rest_run-01_bold.json containing {"run": 1}.
3. Attempt to initialize the layout: layout = BIDSLayout(dset_dir).

Expected behavior: PyBIDS should recognize they are numerically equivalent.
Actual behavior: Crashes with BIDSConflictingValuesError: Conflicting values found for entity 'run'... (value='01') versus its JSON sidecar (value='1').

Suggested Fix

PyBIDS should attempt to coerce both values to a common numeric type (or utilize the internal entity.astype logic) to verify if they are numerically equivalent before raising a genuine user conflict error.