[FSSDK-12368] Add Xcode project linking and implement all test cases

Backport fixes from PR #628 to make PR #629 complete:

1. Add DecisionServiceTests_LocalHoldouts.swift to Xcode project
   - Added PBXBuildFile entries for both test targets
   - Added PBXFileReference entry
   - File now discovered and runs in Xcode builds

2. Replace stub tests with fully implemented integration tests (15 tests)
   - Global holdouts (2 tests)
   - Local holdouts for experiment rules (3 tests)
   - Local holdouts for delivery rules (2 tests)
   - Multiple holdouts (2 tests)
   - Cross-flag and precedence (3 tests)
   - Edge cases (3 tests)

All tests use decide_datafile, MockBucketer for controlled bucketing,
and assert correct decision behavior.

This makes PR #629 feature-complete and ready for merge.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: muzahidul-opti

OptimizelySwiftSDK.xcodeproj/project.pbxproj

@@ -2119,6 +2119,8 @@
 		98AC984B2DB8FFE0001405DD /* DecisionServiceTests_Holdouts.swift in Sources */ = {isa = PBXBuildFile; fileRef = 98AC98482DB8FC29001405DD /* DecisionServiceTests_Holdouts.swift */; };
 		98AC985E2DBA6721001405DD /* OptimizelyUserContextTests_Decide_With_Holdouts_Reasons.swift in Sources */ = {isa = PBXBuildFile; fileRef = 98AC985D2DBA6721001405DD /* OptimizelyUserContextTests_Decide_With_Holdouts_Reasons.swift */; };
 		98AC985F2DBA6721001405DD /* OptimizelyUserContextTests_Decide_With_Holdouts_Reasons.swift in Sources */ = {isa = PBXBuildFile; fileRef = 98AC985D2DBA6721001405DD /* OptimizelyUserContextTests_Decide_With_Holdouts_Reasons.swift */; };
+		98C2DF242F900669003F2443 /* DecisionServiceTests_LocalHoldouts.swift in Sources */ = {isa = PBXBuildFile; fileRef = 98C2DF232F900669003F2443 /* DecisionServiceTests_LocalHoldouts.swift */; };
+		98C2DF252F900669003F2443 /* DecisionServiceTests_LocalHoldouts.swift in Sources */ = {isa = PBXBuildFile; fileRef = 98C2DF232F900669003F2443 /* DecisionServiceTests_LocalHoldouts.swift */; };
 		98D5AE842DBB91C0000D5844 /* OptimizelyUserContextTests_Decide_Holdouts.swift in Sources */ = {isa = PBXBuildFile; fileRef = 98D5AE832DBB91C0000D5844 /* OptimizelyUserContextTests_Decide_Holdouts.swift */; };
 		98D5AE852DBB91C0000D5844 /* OptimizelyUserContextTests_Decide_Holdouts.swift in Sources */ = {isa = PBXBuildFile; fileRef = 98D5AE832DBB91C0000D5844 /* OptimizelyUserContextTests_Decide_Holdouts.swift */; };
 		98F28A1D2E01940500A86546 /* Cmab.swift in Sources */ = {isa = PBXBuildFile; fileRef = 98F28A1C2E01940500A86546 /* Cmab.swift */; };
@@ -2635,6 +2637,7 @@
 		98AC98452DB7B762001405DD /* BucketTests_HoldoutToVariation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BucketTests_HoldoutToVariation.swift; sourceTree = "<group>"; };
 		98AC98482DB8FC29001405DD /* DecisionServiceTests_Holdouts.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DecisionServiceTests_Holdouts.swift; sourceTree = "<group>"; };
 		98AC985D2DBA6721001405DD /* OptimizelyUserContextTests_Decide_With_Holdouts_Reasons.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OptimizelyUserContextTests_Decide_With_Holdouts_Reasons.swift; sourceTree = "<group>"; };
+		98C2DF232F900669003F2443 /* DecisionServiceTests_LocalHoldouts.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DecisionServiceTests_LocalHoldouts.swift; sourceTree = "<group>"; };
 		98D5AE832DBB91C0000D5844 /* OptimizelyUserContextTests_Decide_Holdouts.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OptimizelyUserContextTests_Decide_Holdouts.swift; sourceTree = "<group>"; };
 		98F28A1C2E01940500A86546 /* Cmab.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Cmab.swift; sourceTree = "<group>"; };
 		98F28A2D2E01968000A86546 /* CmabTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CmabTests.swift; sourceTree = "<group>"; };
@@ -3177,6 +3180,7 @@
 				6E0207A7272A11CF008C3711 /* NetworkReachabilityTests.swift */,
 				6E75198B22C5211100B2B157 /* NotificationCenterTests.swift */,
 				84861810286D0B8900B7F41B /* OdpEventManagerTests.swift */,
+				98C2DF232F900669003F2443 /* DecisionServiceTests_LocalHoldouts.swift */,
 				8486180E286D0B8900B7F41B /* OdpManagerTests.swift */,
 				8486180D286D0B8900B7F41B /* OdpSegmentManagerTests.swift */,
 				98F28A512E02E81500A86546 /* CMABClientTests.swift */,
@@ -5191,6 +5195,7 @@
 				6E6522EB278E4F3800954EA1 /* OdpManager.swift in Sources */,
 				6E75187922C520D400B2B157 /* Variation.swift in Sources */,
 				6E75191522C520D500B2B157 /* BackgroundingCallbacks.swift in Sources */,
+				98C2DF242F900669003F2443 /* DecisionServiceTests_LocalHoldouts.swift in Sources */,
 				6E75195D22C520D500B2B157 /* OPTBucketer.swift in Sources */,
 				6E9B117622C5487100C22D81 /* DatafileHandlerTests.swift in Sources */,
 				84E2E97F2855875E001114AB /* OdpEventManager.swift in Sources */,
@@ -5494,6 +5499,7 @@
 				84861813286D0B8900B7F41B /* OdpManagerTests.swift in Sources */,
 				6E7516FD22C520D400B2B157 /* OptimizelyLogLevel.swift in Sources */,
 				6E75187322C520D400B2B157 /* Variation.swift in Sources */,
+				98C2DF252F900669003F2443 /* DecisionServiceTests_LocalHoldouts.swift in Sources */,
 				6E7517E322C520D400B2B157 /* DefaultDecisionService.swift in Sources */,
 				6E75179922C520D400B2B157 /* DataStoreQueueStackImpl+Extension.swift in Sources */,
 				6E9B115C22C5486E00C22D81 /* DatafileHandlerTests.swift in Sources */,