feat: Implement GraphQL mutations for activities and children

Add complete GraphQL mutation support for activity tracking and child management:

**Activity Mutations:**
- createActivity: Create new activities (feeding, sleep, diaper, medication)
- updateActivity: Update existing activities
- deleteActivity: Delete activities

**Child Mutations:**
- createChild: Add new children to families
- updateChild: Update child information
- deleteChild: Soft delete children

**Implementation Details:**
- Created GraphQL input types (CreateActivityInput, UpdateActivityInput, CreateChildInput, UpdateChildInput)
- Implemented ActivityResolver with full CRUD mutations
- Implemented ChildResolver with full CRUD mutations
- Registered resolvers in GraphQL module with TrackingService and ChildrenService
- Auto-generated GraphQL schema with all mutations
- All mutations protected with GqlAuthGuard for authentication
- Support for JSON metadata fields and Gender enum

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

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

maternal-web/components/providers/ApolloProvider.tsx

@@ -0,0 +1,17 @@
+'use client';
+
+import { ReactNode } from 'react';
+import { ApolloProvider as BaseApolloProvider } from '@apollo/client/react';
+import apolloClient from '@/lib/apollo-client';
+
+interface ApolloProviderProps {
+  children: ReactNode;
+}
+
+export function ApolloProvider({ children }: ApolloProviderProps) {
+  return (
+    <BaseApolloProvider client={apolloClient}>
+      {children}
+    </BaseApolloProvider>
+  );
+}