Add Firestore security rules and deployment scripts

- Add firestore.rules for SMTP config permissions
- Add deployment scripts for Firestore rules
- Update Admin component with better error handling
- Update README with deployment instructions

firestore.rules

@@ -0,0 +1,24 @@
+rules_version = '2';
+service cloud.firestore {
+  match /databases/{database}/documents {
+    // Allow authenticated users to read/write their own data
+    match /users/{userId} {
+      allow read, write: if request.auth != null && request.auth.uid == userId;
+    }
+
+    // Allow authenticated users to read/write prayers
+    match /prayers/{prayerId} {
+      allow read, write: if request.auth != null;
+    }
+
+    // Allow authenticated users to read/write config (for admin settings)
+    match /config/{configId} {
+      allow read, write: if request.auth != null;
+    }
+
+    // Allow anyone to read public data (if needed in future)
+    match /public/{document} {
+      allow read: if true;
+    }
+  }
+}