Add unified DataManager as single source of truth for all app data

- Create DataManager.kt with StateFlows for all cached data:
  - Authentication (token, user)
  - Residences, tasks, documents, contractors
  - Subscription status and upgrade triggers
  - All lookup data (residence types, task categories, etc.)
  - Theme preferences and state metadata

- Add PersistenceManager with platform-specific implementations:
  - Android: SharedPreferences
  - iOS: NSUserDefaults
  - JVM: Properties file
  - WasmJS: localStorage

- Migrate APILayer to update DataManager on every API response
- Update Kotlin ViewModels to use DataManager for token access
- Deprecate LookupsRepository (delegates to DataManager)
- Create iOS DataManagerObservable Swift wrapper for SwiftUI
- Update iOS auth flow to use DataManager.isAuthenticated()

Data flow: User Action → API Call → DataManager Updated → All Screens React

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

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

composeApp/src/iosMain/kotlin/com/example/casera/data/PersistenceManager.ios.kt

@@ -0,0 +1,42 @@
+package com.example.casera.data
+
+import platform.Foundation.NSUserDefaults
+
+/**
+ * iOS implementation of PersistenceManager using NSUserDefaults.
+ */
+actual class PersistenceManager {
+    private val defaults = NSUserDefaults.standardUserDefaults
+
+    actual fun save(key: String, value: String) {
+        defaults.setObject(value, forKey = key)
+        defaults.synchronize()
+    }
+
+    actual fun load(key: String): String? {
+        return defaults.stringForKey(key)
+    }
+
+    actual fun remove(key: String) {
+        defaults.removeObjectForKey(key)
+        defaults.synchronize()
+    }
+
+    actual fun clear() {
+        // Get all keys with our prefix and remove them
+        val dict = defaults.dictionaryRepresentation()
+        dict.keys.forEach { key ->
+            val keyStr = key as? String ?: return@forEach
+            if (keyStr.startsWith("dm_")) {
+                defaults.removeObjectForKey(keyStr)
+            }
+        }
+        defaults.synchronize()
+    }
+
+    companion object {
+        private val instance by lazy { PersistenceManager() }
+
+        fun getInstance(): PersistenceManager = instance
+    }
+}