Add residence sharing via .casera files

- Add SharedResidence model and package type detection for .casera files
- Add generateSharePackage API endpoint integration
- Create ResidenceSharingManager for iOS and Android
- Add share button to residence detail screens (owner only)
- Add residence import handling with confirmation dialogs
- Update Quick Look extensions to show house icon for residence packages
- Route .casera imports by type (contractor vs residence)

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

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

composeApp/src/iosMain/kotlin/com/example/casera/platform/ResidenceImportHandler.ios.kt

@@ -0,0 +1,17 @@
+package com.example.casera.platform
+
+import androidx.compose.runtime.Composable
+import com.example.casera.models.JoinResidenceResponse
+
+/**
+ * iOS implementation is a no-op - import is handled in Swift layer via ResidenceSharingManager.swift.
+ * The iOS iOSApp.swift handles file imports directly.
+ */
+@Composable
+actual fun ResidenceImportHandler(
+    pendingResidenceImportUri: Any?,
+    onClearResidenceImport: () -> Unit,
+    onImportSuccess: (JoinResidenceResponse) -> Unit
+) {
+    // No-op on iOS - import handled in Swift layer
+}

composeApp/src/iosMain/kotlin/com/example/casera/platform/ResidenceSharing.ios.kt

@@ -0,0 +1,15 @@
+package com.example.casera.platform
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import com.example.casera.models.Residence
+
+/**
+ * iOS implementation is a no-op - sharing is handled in Swift layer via ResidenceSharingManager.swift.
+ */
+@Composable
+actual fun rememberShareResidence(): Pair<ResidenceSharingState, (Residence) -> Unit> {
+    val state = remember { ResidenceSharingState() }
+    val noOp: (Residence) -> Unit = { /* No-op on iOS - handled in Swift layer */ }
+    return Pair(state, noOp)
+}