Operator integration hardening

[GavriloviciEduard]

Mark the type contribution you are making:

• Experimental feature (new functionality that can be selectively enabled/disabled)
• Bug fix (non-breaking change which fixes an issue)

Description

This is a hardening pass on the existing Epilogue Operator experimental feature. It fixes data-loss and UI edge cases surfaced during on-device testing, plus improves cartridge detection.

What this PR changes:

• Save reliability / data integrity: hardens cartridge save handling against data loss (writeback guards), and restores game dismissal when its cartridge is re-inserted.
• Launch gating on a verified save: a game launched from a cartridge now waits for its save to be verified, recovers a failed read, and prompts the user before ever starting without save data.
• Cartridge detection: more reliable detection of cartridge removal and SNES carts, so a removed cartridge no longer reads as still inserted.
• Import UX: clearer progress feedback and toasts during cartridge import, and fixes to library/overlay glitches while importing.

Why is this change necessary?
On-device testing of the shipped Operator feature exposed several ways a cartridge session could lose save data or leave the library UI in a wrong/flashing state (e.g. an interrupted save write, a removed cartridge still reading as inserted, launching before the save was read).

Why did you decide on this solution?

• Kept all changes behind the existing operatorDevice flag and inside the isolated +Operator Swift extensions / DeltaOperator + OperatorKit layer, so upstream Delta code paths are barely touched.
• Chose to gate launch on a verified save (with recovery + user prompt) rather than launch optimistically, since silently starting without save data risks overwriting the cartridge.
• Reworked cartridge-presence detection so a removed cartridge is recognized promptly instead of lingering as "inserted".

Testing

Tested on the following, all running the latest iOS release:

• iPhone 16
• iPhone 16 Pro Max
• iPhone 17 Pro

Checklist

General (All PRs)

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I've tested my changes with different device + OS version configurations

Experimental Feature-specific

• Added property to ExperimentalFeatures struct annotated with @Feature
• Uses @Option's to persist all feature-related data
• Locked all behavior changes behind ExperimentalFeatures.shared.[feature].isEnabled runtime check
• Isolates changes to separate files as much as possible (e.g. via Swift extensions)