[Bugfix] Asset Browser shows cluttered/confusing source folders alongside .untoldpack files #152

Problem

In the Asset Browser, exported models show up as confusing duplicate-looking entries. For example, in a Models/ folder:

bl/                 (source folder: .blend, HDR, Textures, per-submesh .untold payloads)
bl.untoldpack        <- this is the thing the user should actually click
gloves/
gloves.untoldpack
soocer_player/
soocer_player.untold

Each asset produces two top-level entries with matching names: a source/working folder (containing the .blend, HDR/, Textures/, and nested per-submesh .untold payload files referenced by the pack manifest) and the actual loadable asset (.untoldpack manifest or standalone .untold). A new user has no way to tell which of the pair is the one to open.

Root cause

This is a browser display issue, not a data layout issue. The cook pipeline's convention (RuntimeExportLocation.swift:28) is intentional: a source Models/bl/bl.blend cooks to a sibling Models/bl.untoldpack, and the folder name matches the pack's stem so re-cooking can find the source again later.

The Asset Browser's folderContentsView (AssetBrowserView+Contents.swift:178) lists every directory entry unconditionally, with no concept that a folder is the source satellite of a sibling pack file. So both show up as flat peers.

Proposed fix

UI-only change, no cook pipeline or export-location changes, no migration needed for existing projects:

• In folderContentsView, suppress a folder from the listing when its name matches the stem of a sibling .untold/.untoldpack file in the same directory.
• Surface the hidden source folder via a "Reveal Source Folder" context-menu item on the asset's row, alongside the existing "Cook to .untold…" action.

Files involved

• AssetBrowserView+Contents.swift:178 (listing logic)
• RuntimeExportLocation.swift:28 (naming convention reference, read-only)