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/androidMain/kotlin/com/example/casera/data/PersistenceManager.android.kt

@@ -0,0 +1,43 @@
+package com.example.casera.data
+
+import android.content.Context
+import android.content.SharedPreferences
+
+/**
+ * Android implementation of PersistenceManager using SharedPreferences.
+ */
+actual class PersistenceManager(context: Context) {
+    private val prefs: SharedPreferences = context.getSharedPreferences(
+        PREFS_NAME,
+        Context.MODE_PRIVATE
+    )
+
+    actual fun save(key: String, value: String) {
+        prefs.edit().putString(key, value).apply()
+    }
+
+    actual fun load(key: String): String? {
+        return prefs.getString(key, null)
+    }
+
+    actual fun remove(key: String) {
+        prefs.edit().remove(key).apply()
+    }
+
+    actual fun clear() {
+        prefs.edit().clear().apply()
+    }
+
+    companion object {
+        private const val PREFS_NAME = "casera_data_manager"
+
+        @Volatile
+        private var instance: PersistenceManager? = null
+
+        fun getInstance(context: Context): PersistenceManager {
+            return instance ?: synchronized(this) {
+                instance ?: PersistenceManager(context.applicationContext).also { instance = it }
+            }
+        }
+    }
+}