refactor: migrate CRM data layer from manual gqlFetch to Apollo Client

Replace custom gqlFetch() with proper Apollo useQuery/useMutation hooks
powered by codegen-generated TypedDocumentNode types. Key changes:

- Add GraphQL SDL schema file and codegen config for typescript-vue-apollo
- Replace all 28 raw .graphql imports with generated typed documents
- Add 12 useQuery() hooks with cache-and-network fetch policy
- Add 17 useMutation() hooks with surgical refetchQueries per mutation
- Optimistic cache update for setContactInboxHidden (instant archive UX)
- Fix contact list subtitle: show lastText instead of channel name
- Migrate login page from gqlFetch to useMutation
- WebSocket realtime now calls Apollo refetch instead of full data reload

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/nuxt.config.ts

@@ -27,6 +27,14 @@ export default defineNuxtConfig({
       default: {
         httpEndpoint: process.env.GRAPHQL_HTTP_ENDPOINT || "http://localhost:3000/api/graphql",
         connectToDevTools: process.dev,
+        httpLinkOptions: {
+          credentials: "include",
+        },
+        defaultOptions: {
+          watchQuery: {
+            fetchPolicy: "cache-and-network",
+          },
+        },
       },
     },
   },