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/jvmMain/kotlin/com/example/casera/data/PersistenceManager.jvm.kt

@@ -0,0 +1,65 @@
+package com.example.casera.data
+
+import java.io.File
+import java.util.Properties
+
+/**
+ * JVM/Desktop implementation of PersistenceManager using Properties file.
+ */
+actual class PersistenceManager {
+    private val properties = Properties()
+    private val storageFile: File
+
+    init {
+        val userHome = System.getProperty("user.home")
+        val appDir = File(userHome, ".casera")
+        if (!appDir.exists()) {
+            appDir.mkdirs()
+        }
+        storageFile = File(appDir, "data.properties")
+        loadProperties()
+    }
+
+    private fun loadProperties() {
+        if (storageFile.exists()) {
+            try {
+                storageFile.inputStream().use { properties.load(it) }
+            } catch (e: Exception) {
+                // Ignore load errors
+            }
+        }
+    }
+
+    private fun saveProperties() {
+        try {
+            storageFile.outputStream().use { properties.store(it, "Casera Data Manager") }
+        } catch (e: Exception) {
+            // Ignore save errors
+        }
+    }
+
+    actual fun save(key: String, value: String) {
+        properties.setProperty(key, value)
+        saveProperties()
+    }
+
+    actual fun load(key: String): String? {
+        return properties.getProperty(key)
+    }
+
+    actual fun remove(key: String) {
+        properties.remove(key)
+        saveProperties()
+    }
+
+    actual fun clear() {
+        properties.clear()
+        saveProperties()
+    }
+
+    companion object {
+        private val instance by lazy { PersistenceManager() }
+
+        fun getInstance(): PersistenceManager = instance
+    }
+}