[Feature] File Provider — Save State & Screenshot Enumeration

[github-actions]

Summary

Add Save States and Screenshots as browsable categories in the Provenance ROM File Provider extension so users can copy-out save states and screenshots from Files.app.

Current State

PR #3607 completed the ROM File ProviderUI extension skeleton. The main NSFileProviderReplicatedExtension (ROM File Provider target) already exposes the full ROM library (Systems / Publishers / Years / Regions / Ratings) with create, read, rename, and delete support. However, save states and screenshots are not yet surfaced.

Goals

• Save States top-level category in Files.app: Provenance / Save States / <Game Title> / <save.pvs>
• Screenshots top-level category: Provenance / Screenshots / <Game Title> / <screenshot.png>
• Read-only: copy-out is allowed; delete is allowed to let users clean up from Files.app
• Each game that has saves/screenshots gets a named sub-folder (ss-game:<md5> / sc-game:<md5>)

Implementation Notes

1. PVPrimitives/RomFileProviderVirtualPath.swift

Add two new cases to RomFileProviderRootCategory:

case saveStates = "cat:savestates"
case screenshots = "cat:screenshots"

Add prefix constants to RomFileProviderVirtualPath:

public static let saveStateGameFolderPrefix = "ss-game:"
public static let saveStateItemPrefix = "ss:"
public static let screenshotGameFolderPrefix = "sc-game:"
public static let screenshotItemPrefix = "sc:"

2. Extensions/ROM File Provider/FileProviderItem.swift

New Kind cases:

• saveStateGameFolder(game: Game, parentItemIdentifier:)
• saveStateFile(id: String, game: Game, date: Date, isAutosave: Bool, userDescription: String?, fileURL: URL?, parentItemIdentifier:)
• screenshotGameFolder(game: Game, parentItemIdentifier:)
• screenshotFile(gameMD5: String, index: Int, imageURL: URL?, parentItemIdentifier:)

3. Extensions/ROM File Provider/RomFileProviderCPDI.swift

Add:

• LocalSaveStateEntry struct (game CPDI snapshot + id + fileURL + date + isAutosave + description)
• LocalScreenshotEntry struct (gameMD5 + index + imageURL)
• loadAllSaveStateEntries() — snapshot all PVSaveState objects (via PVGame.saveStates) that have a local file
• loadAllScreenshotEntries() — snapshot all PVGame.screenShots that have a local file
• saveStateGameFolders() — distinct game snapshots that have at least one save state
• screenshotGameFolders() — distinct game snapshots that have at least one screenshot

4. Extensions/ROM File Provider/FileProviderEnumerator.swift

Wire the new prefixes in buildItems:

• cat:savestates → list game folders (ss-game:<md5>) for games that have save states
• ss-game:<md5> → list individual save state items (ss:<id>)
• cat:screenshots → list game folders (sc-game:<md5>) for games that have screenshots
• sc-game:<md5> → list individual screenshot items (sc:<md5>:<index>)

5. Extensions/ROM File Provider/FileProviderExtension.swift

• resolveItem — handle ss-game:, ss:, sc-game:, sc: prefixes
• fetchContents — handle ss:<id> (serve .file?.url) and sc:<md5>:<index> (serve screenshot URL)
• deleteItem — handle save state and screenshot deletion
• Read-only guard on modifyItem for save state / screenshot items

Acceptance Criteria

• Provenance / Save States folder visible in Files.app
• Save states grouped by game name sub-folder
• Save state files can be copied out from Files.app
• Provenance / Screenshots folder visible in Files.app
• Screenshots grouped by game name sub-folder
• Screenshot images can be copied out from Files.app
• Deletion works: deleting a save state from Files.app removes it from Realm + filesystem

Related

Part of #3595
Part of #2659 (Import / Export / Share epic)