Refactor StoreKit 2 subscription system and add interactive vote widget

## StoreKit 2 Refactor
- Rewrote IAPManager with clean enum-based state model (SubscriptionState)
- Added native SubscriptionStoreView for iOS 17+ purchase UI
- Subscription status now checked on every app launch
- Synced subscription status to UserDefaults for widget access
- Simplified PurchaseButtonView and IAPWarningView
- Removed unused StatusInfoView

## Interactive Vote Widget
- New FeelsVoteWidget with App Intents for mood voting
- Subscribers can vote directly from widget, shows stats after voting
- Non-subscribers see "Tap to subscribe" which opens subscription store
- Added feels:// URL scheme for deep linking

## Firebase Removal
- Commented out Firebase imports and initialization
- EventLogger now prints to console in DEBUG mode only

## Other Changes
- Added fallback for Core Data when App Group unavailable
- Added new localization strings for subscription UI
- Updated entitlements and Info.plist

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

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

Shared/views/FeelsSubscriptionStoreView.swift

@@ -0,0 +1,47 @@
+//
+//  FeelsSubscriptionStoreView.swift
+//  Feels
+//
+//  Native StoreKit 2 subscription purchase view.
+//
+
+import SwiftUI
+import StoreKit
+
+struct FeelsSubscriptionStoreView: View {
+    @Environment(\.dismiss) private var dismiss
+    @EnvironmentObject var iapManager: IAPManager
+
+    var body: some View {
+        SubscriptionStoreView(groupID: IAPManager.subscriptionGroupID) {
+            VStack(spacing: 16) {
+                Image(systemName: "heart.fill")
+                    .font(.system(size: 60))
+                    .foregroundStyle(.pink)
+
+                Text(String(localized: "subscription_store_title"))
+                    .font(.title)
+                    .bold()
+
+                Text(String(localized: "subscription_store_subtitle"))
+                    .font(.body)
+                    .foregroundStyle(.secondary)
+                    .multilineTextAlignment(.center)
+            }
+            .padding()
+        }
+        .subscriptionStoreControlStyle(.prominentPicker)
+        .storeButton(.visible, for: .restorePurchases)
+        .subscriptionStoreButtonLabel(.multiline)
+        .onInAppPurchaseCompletion { _, result in
+            if case .success(.success(_)) = result {
+                dismiss()
+            }
+        }
+    }
+}
+
+#Preview {
+    FeelsSubscriptionStoreView()
+        .environmentObject(IAPManager())
+}