Add Korean localization

[himomohi]

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

Adds first-party Korean localization support for Delta and addresses #507.

This change:

• adds Korean translations for 834 runtime strings, storyboard/XIB resources, and privacy usage descriptions
• registers ko resources in the Xcode project for all existing localized resource variants
• enables Swift string extraction for the Delta Debug and Release configurations
• converts remaining user-visible hardcoded strings in settings, controller editing, repair flows, What's New, RetroAchievements, Patreon, and Lu to localized lookups
• preserves product names, URLs, format placeholders, newlines, logging behavior, and dynamic attributed-string ranges

Korean gaming terminology is kept consistent throughout the app, including:

• Save State → 세이브 스테이트
• Game Save → 세이브 파일
• Cheat → 치트
• Controller Skin → 컨트롤러 스킨

Testing

No iOS device or simulator configuration has been tested yet. This pull request is intentionally a draft because the current environment has Command Line Tools but not the full Xcode app, so xcodebuild, ibtool, simulator, and physical-device runtime validation are not available.

Static validation completed:

• plutil -lint Delta/ko.lproj/*.strings Delta.xcodeproj/project.pbxproj
• git diff --check origin/main...HEAD
• parsed every modified Swift source with swiftc -frontend -parse
• verified 834 unique Korean Localizable.strings keys with no duplicates
• verified all 585 pre-existing extracted keys remain present
• verified placeholder token, newline, and URL parity
• verified all 11 localized Xcode resource variant groups include ko
• verified storyboard/XIB source files themselves are unchanged
• independently reviewed the frozen diff with no actionable P0–P3 findings

Tested Configurations:

• Static validation only — full Xcode and iOS runtime testing pending

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 — requires a full Xcode build
• 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)