Replace provisional Aender frame naming and assets

[xefensor]

Goal

Replace the development-only Aender portal frame identity with an approved final name and original visual direction.

Scope

• choose the final player-facing name
• replace retold:dev_aender_portal_frame visuals with approved original assets
• decide whether the internal identifier should be migrated
• preserve existing worlds if identifiers change
• update recipes, loot, language, documentation, screenshots, and credits
• remove placeholder disclosures only after every provisional asset is actually replaced

Asset requirements

All creative work must have documented authorship, source, permission, and required attribution in ASSET_CREDITS.md.

Target: v0.3.0