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/wasmJsMain/kotlin/com/example/casera/data/PersistenceManager.wasmJs.kt

@@ -0,0 +1,38 @@
+package com.example.casera.data
+
+import kotlinx.browser.localStorage
+
+/**
+ * WasmJS implementation of PersistenceManager using browser localStorage.
+ */
+actual class PersistenceManager {
+    actual fun save(key: String, value: String) {
+        localStorage.setItem(key, value)
+    }
+
+    actual fun load(key: String): String? {
+        return localStorage.getItem(key)
+    }
+
+    actual fun remove(key: String) {
+        localStorage.removeItem(key)
+    }
+
+    actual fun clear() {
+        // Remove all items with our prefix
+        val keysToRemove = mutableListOf<String>()
+        for (i in 0 until localStorage.length) {
+            val key = localStorage.key(i) ?: continue
+            if (key.startsWith("dm_")) {
+                keysToRemove.add(key)
+            }
+        }
+        keysToRemove.forEach { localStorage.removeItem(it) }
+    }
+
+    companion object {
+        private val instance by lazy { PersistenceManager() }
+
+        fun getInstance(): PersistenceManager = instance
+    }
+}