Potential Fields to Add to the MARC Bot

### Proposal

As I discussed with @scottbarnes, I believe the MARC Bot could benefit from the following fields:

247: Former Title (when relevant)
306: Playing Time (for audiobooks)
341: Accessibility Content - subfields $b (Textual assistive features), $c (Visual assistive features), and $d (Auditory assistive features), in particular
370: Associated Place - subfield $c (Associated country)

@hornc, @tfmorris. I'm open to discussing further.

### Justification

### Breakdown

#### Requirements Checklist

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#### Related files

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#### Stakeholders

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#### Instructions for Contributors

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Start by locating the MARC Bot implementation and existing handling for MARC fields. Review how fields 247, 306, 341, and 370 are represented and identify the relevant MARC requirements before defining the scope. Done should include an agreed field list, implementation guidance, and tests or verification for the supported subfields.

Written by the indexing model from the issue text.