Add PostHog analytics integration for Android and iOS

Implement comprehensive analytics tracking across both platforms:

Android (Kotlin):
- Add PostHog SDK dependency and initialization in MainActivity
- Create expect/actual pattern for cross-platform analytics (commonMain/androidMain/iosMain/jvmMain/jsMain/wasmJsMain)
- Track screen views: registration, login, residences, tasks, contractors, documents, notifications, profile
- Track key events: user_registered, user_signed_in, residence_created, task_created, contractor_created, document_created
- Track paywall events: contractor_paywall_shown, documents_paywall_shown
- Track sharing events: residence_shared, contractor_shared
- Track theme_changed event

iOS (Swift):
- Add PostHog iOS SDK via SPM
- Create PostHogAnalytics wrapper and AnalyticsEvents constants
- Initialize SDK in iOSApp with session replay support
- Track same screen views and events as Android
- Track user identification after login/registration

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

iosApp/iosApp.xcodeproj/project.pbxproj

@@ -14,6 +14,7 @@
 		1C81F2772EE416EF000739EA /* CaseraQLPreview.appex in Embed Foundation Extensions */ = {isa = PBXBuildFile; fileRef = 1C81F2692EE416EE000739EA /* CaseraQLPreview.appex */; settings = {ATTRIBUTES = (RemoveHeadersOnCopy, ); }; };
 		1C81F2822EE41BB6000739EA /* QuickLookThumbnailing.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 1C81F2812EE41BB6000739EA /* QuickLookThumbnailing.framework */; };
 		1C81F2892EE41BB6000739EA /* CaseraQLThumbnail.appex in Embed Foundation Extensions */ = {isa = PBXBuildFile; fileRef = 1C81F2802EE41BB6000739EA /* CaseraQLThumbnail.appex */; settings = {ATTRIBUTES = (RemoveHeadersOnCopy, ); }; };
+		1C81F3902EE69AF1000739EA /* PostHog in Frameworks */ = {isa = PBXBuildFile; productRef = 1C81F38F2EE69AF1000739EA /* PostHog */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -256,6 +257,7 @@
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				1C81F3902EE69AF1000739EA /* PostHog in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -450,6 +452,7 @@
 			);
 			name = Casera;
 			packageProductDependencies = (
+				1C81F38F2EE69AF1000739EA /* PostHog */,
 			);
 			productName = iosApp;
 			productReference = 96A3DDC05E14B3F83E56282F /* Casera.app */;
@@ -496,6 +499,9 @@
 			);
 			mainGroup = 86BC7E88090398B44B7DB0E4;
 			minimizedProjectReferenceProxies = 1;
+			packageReferences = (
+				1C81F38E2EE69698000739EA /* XCRemoteSwiftPackageReference "posthog-ios" */,
+			);
 			preferredProjectObjectVersion = 77;
 			productRefGroup = FA6022B7B844191C54E57EB4 /* Products */;
 			projectDirPath = "";
@@ -1198,6 +1204,25 @@
 			defaultConfigurationName = Release;
 		};
 /* End XCConfigurationList section */
+
+/* Begin XCRemoteSwiftPackageReference section */
+		1C81F38E2EE69698000739EA /* XCRemoteSwiftPackageReference "posthog-ios" */ = {
+			isa = XCRemoteSwiftPackageReference;
+			repositoryURL = "https://github.com/PostHog/posthog-ios.git";
+			requirement = {
+				kind = upToNextMajorVersion;
+				minimumVersion = 3.35.1;
+			};
+		};
+/* End XCRemoteSwiftPackageReference section */
+
+/* Begin XCSwiftPackageProductDependency section */
+		1C81F38F2EE69AF1000739EA /* PostHog */ = {
+			isa = XCSwiftPackageProductDependency;
+			package = 1C81F38E2EE69698000739EA /* XCRemoteSwiftPackageReference "posthog-ios" */;
+			productName = PostHog;
+		};
+/* End XCSwiftPackageProductDependency section */
 	};
 	rootObject = 6A3E1D84F9F1A2FD92A75A6C /* Project object */;
 }

iosApp/iosApp.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -0,0 +1,15 @@
+{
+  "originHash" : "47cbe4ef2adc7155b834c1fb5ae451e260f9ef6ba19f0658c4fcafd3565fad48",
+  "pins" : [
+    {
+      "identity" : "posthog-ios",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/PostHog/posthog-ios.git",
+      "state" : {
+        "revision" : "fac9fc77380d2a38c3389f3cf4505a534921ee41",
+        "version" : "3.35.1"
+      }
+    }
+  ],
+  "version" : 3
+}