feat: Shared Scheme + StoreKit Configuration (Test Action 需 Xcode)

- xcshareddata/xcschemes/AIStudyApp.xcscheme (Shared)
- LaunchAction 引用 Products.storekit (本地 StoreKit 测试)
- Products.storekit: Premium Monthly(28 CNY) + Yearly(198 CNY)
- Build/Launch/Profile/Archive 全部就绪

Test Target 添加步骤（Xcode GUI, 2 分钟）:
  1. File → New → Target → Unit Testing Bundle → AIStudyAppTests
  2. 移除自动生成的 AIStudyAppTests.swift
  3. 在 Build Phases → Compile Sources 添加 AIStudyAppTests/ 下 28 个文件
  4. Edit Scheme → Test → + → AIStudyAppTests
  5. Test Action → Options → StoreKit Configuration = Products.storekit

注: pbxproj objectVersion=77 使用文件系统同步组，无法通过 CLI 安全添加 Target

AIStudyApp/AIStudyApp.xcodeproj/xcshareddata/xcschemes/AIStudyApp.xcscheme

@@ -0,0 +1,84 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "2600"
+   version = "1.7">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES"
+      buildArchitectures = "Automatic">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "05F6CD1A2FA886330043A7BC"
+               BuildableName = "AIStudyApp.app"
+               BlueprintName = "AIStudyApp"
+               ReferencedContainer = "container:AIStudyApp.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      enableAddressSanitizer = "NO"
+      enableThreadSanitizer = "NO"
+      enableUBSanitizer = "NO"
+      disableMainThreadChecker = "NO">
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+      <StoreKitConfigurationFileReference
+         identifier = "Products.storekit">
+      </StoreKitConfigurationFileReference>
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "05F6CD1A2FA886330043A7BC"
+            BuildableName = "AIStudyApp.app"
+            BlueprintName = "AIStudyApp"
+            ReferencedContainer = "container:AIStudyApp.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "05F6CD1A2FA886330043A7BC"
+            BuildableName = "AIStudyApp.app"
+            BlueprintName = "AIStudyApp"
+            ReferencedContainer = "container:AIStudyApp.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>