Implement Single-Step Resampling to Template

[nx10]

Compose transforms and apply in one step to minimize resampling.

• Create src/rbc/core/functional/resampling.py
• Compose per volume: motion → distortion → bold2anat → anat2template
• Apply with FSL applywarp or ANTs antsApplyTransforms
• Output to 2mm isotropic template
• Use slice-timing-corrected input
• Unit test for transform ordering
• Integration test (~3-5 min)
• Full test marked as slow (~10-15 min)

Output: space-template_desc-preproc_bold

Requires: Issues #5, #8, anatomical registration, 2mm MNI template

Reference: Step 13: Transform Composition and Step 14: Single-Step Resampling