Add swi and minIP suffixes for susceptibility weighted imaging

[astewartau]

Summary

Adds support for susceptibility weighted images (swi) and minimum intensity projections (minIP) as non-parametric anatomical MRI suffixes, addressing the remaining gaps identified in #1566.

• Adds swi and minIP suffix definitions to src/schema/objects/suffixes.yaml
• Adds a file rule group in src/schema/rules/files/raw/anat.yaml with standard MRI entities (no echo or part, since multi-echo combination occurs before SWI generation)
• Adds swi and minIP to the non-parametric suffix table and filename template in the MRI documentation

These suffixes are classified as non-parametric (arbitrary intensity scale), consistent with how T2starw and other contrast-weighted images are handled. Like Chimap and other parametric maps, they can appear in raw datasets when pre-generated by the scanner, or in derivative datasets when computed offline.

Ref: #1566 (comment)

Test plan

• Schema validation passes
• Rendered docs show swi and minIP in the non-parametric suffix table and filename templates
• Example dataset validates (see companion PR in bids-examples)

[effigies]

Are these both raw images (i.e., you get them off a scanner) or should minIP be a derivative?

Also, is minIP ever sensibly used in a non-SWI context?

[tsalo]

I think the scanner will produce minIP images. Also, I got minIP images from an angio scan in ds002278 (see the JSON).

[effigies]

How are minIP used? Are they for looking at or processing? If just looking at, minIP as a suffix seems fine, but if not, maybe it's more a stat-minIP_swi than a mod-swi_minIP?

[tsalo]

@astewartau would be better able to answer that, but I think they're for looking at.