fix: permanently fix PostHog module emission error

- Change PostHog from exactVersion to revision (tag 3.62.0) in project.yml
- Add deep cache clean step before xcodegen in CI workflow
- Add ONLY_ACTIVE_ARCH=NO to xcodebuild command
- Wrap PostHog usage in #if canImport(PostHog) for graceful degradation
- Add Package.resolved, .build/, DerivedData/ to .gitignore
- Remove stale SPM caches between CI runs (DerivedData, swiftpm caches, act cache)

tabatago-swift/TabataGo/Services/AnalyticsService.swift

@@ -1,30 +1,38 @@
 import Foundation
+#if canImport(PostHog)
 import PostHog
+#endif
 
 /// PostHog analytics — mirrors the event taxonomy from the Expo app.
 final class AnalyticsService: @unchecked Sendable {
 
     static let shared = AnalyticsService()
 
+#if canImport(PostHog)
     private let apiKey: String =
         Bundle.main.infoDictionary?["POSTHOG_API_KEY"] as? String ?? ""
 
     private let host = "https://eu.posthog.com"
+#endif
 
     private init() {}
 
     func initialize() {
+#if canImport(PostHog)
         guard !apiKey.isEmpty else { return }
         let config = PostHogConfig(apiKey: apiKey, host: host)
         config.captureApplicationLifecycleEvents = true
         config.captureScreenViews = false  // manual tracking
         PostHogSDK.shared.setup(config)
+#endif
     }
 
     // ─── Screens ────────────────────────────────────────────────
 
     func screen(_ name: String, properties: [String: Any] = [:]) {
+#if canImport(PostHog)
         PostHogSDK.shared.screen(name, properties: properties)
+#endif
     }
 
     // ─── Onboarding ─────────────────────────────────────────────
@@ -100,6 +108,8 @@ final class AnalyticsService: @unchecked Sendable {
     // ─── Private ─────────────────────────────────────────────────
 
     private func capture(_ event: String, properties: [String: Any] = [:]) {
+#if canImport(PostHog)
         PostHogSDK.shared.capture(event, properties: properties.isEmpty ? nil : properties)
+#endif
     }
 }