feat: add ability to substitute media types for attachments #106

[andrii-novikov]

Applicable issues

Implements #106

Description of changes

Adds the ability to substitute attachment media types

Changes

• New substitute_media_type utility in common/utils.py that maps attachment MIME types via a configurable dictionary
• New media_type_substitution field on AttachmentConfig
• Applied substitution in StagedBaseTool attachment pipeline — runs after supported_types filtering but before propagate_types_to_choice check, so propagation uses the substituted type

Checklist

• Title of the pull request follows Conventional Commits specification
• Documentation is updated/created (if applicable)
• Changes are tested on review environment
• App schema changes are backward compatible
• Integration tests pass

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[andrii-novikov]

/deploy-review

GitHub actions run: 23548439724

Stage	Status
deploy-review	Success ✅
matrix.application	Skipped ➖

[VinShurik]

add (#106) to title