Preserve Glacier RFL chunks through Alpine RED saves

[GooberRF]

• Retain Glacier-specific chunks when RFLs loaded and re-saved in level editor

[Copilot]

Pull request overview

This PR updates AlpineEditor’s RFL load/save path to preserve Glacier-specific (unknown) RFL chunks by capturing them verbatim during load and re-emitting them during save, so Glacier-authored metadata isn’t lost when round-tripping through Alpine RED.

Changes:

• Add identification helpers and an in-memory container (retained_chunks) for Glacier-specific RFL chunks.
• Hook RFL chunk loading to capture 0x6ED***** chunk payloads verbatim and hook saving to write them back out.
• Document the behavior change in the changelog.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
editor_patch/level.h	Adds Glacier chunk ID detection helpers and storage (RetainedRflChunk, retained_chunks) on AlpineLevelProperties.
editor_patch/level.cpp	Implements retained-chunk deserialize/serialize and wires it into the existing load/save injections.
docs/CHANGELOG.md	Notes Glacier chunk retention in the upcoming release changelog.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.