feat: remove CommunicationsQuery, load messages on-demand only

- Remove bulk CommunicationsQuery from useContacts (was loading ALL
  messages for ALL contacts on init)
- Rebuild commThreads from contacts + contactInboxes using the new
  lastMessageText field from Phase 1
- Per-contact messages now load on-demand via getClientTimeline
- Remove commItems from useWorkspaceRouting, use clientTimelineItems

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

frontend/app/composables/useContacts.ts

@@ -1,9 +1,6 @@
 import { ref, computed, watch, watchEffect, type ComputedRef } from "vue";
 import { useQuery } from "@vue/apollo-composable";
-import {
-  ContactsQueryDocument,
-  CommunicationsQueryDocument,
-} from "~~/graphql/generated";
+import { ContactsQueryDocument } from "~~/graphql/generated";
 
 export type Contact = {
   id: string;
@@ -11,6 +8,8 @@ export type Contact = {
   avatar: string;
   channels: string[];
   lastContactAt: string;
+  lastMessageText: string;
+  lastMessageChannel: string;
   description: string;
 };
 
@@ -41,32 +40,13 @@ export function useContacts(opts: { apolloAuthReady: ComputedRef<boolean> }) {
     { enabled: opts.apolloAuthReady },
   );
 
-  const { result: communicationsResult, refetch: refetchCommunications } = useQuery(
-    CommunicationsQueryDocument,
-    null,
-    { enabled: opts.apolloAuthReady },
-  );
-
   const contacts = ref<Contact[]>([]);
-  const commItems = ref<CommItem[]>([]);
 
   watch(
-    [() => contactsResult.value?.contacts, () => communicationsResult.value?.communications],
-    ([rawContacts, rawComms]) => {
+    () => contactsResult.value?.contacts,
+    (rawContacts) => {
       if (!rawContacts) return;
-      const contactsList = [...rawContacts] as Contact[];
-      const commsList = (rawComms ?? []) as CommItem[];
-
-      const byName = new Map<string, Set<string>>();
-      for (const item of commsList) {
-        if (!byName.has(item.contact)) byName.set(item.contact, new Set());
-        byName.get(item.contact)?.add(item.channel);
-      }
-      contacts.value = contactsList.map((c) => ({
-        ...c,
-        channels: Array.from(byName.get(c.name) ?? c.channels ?? []),
-      }));
-      commItems.value = commsList;
+      contacts.value = [...rawContacts] as Contact[];
     },
     { immediate: true },
   );
@@ -166,7 +146,6 @@ export function useContacts(opts: { apolloAuthReady: ComputedRef<boolean> }) {
 
   return {
     contacts,
-    commItems,
     contactSearch,
     selectedChannel,
     sortMode,
@@ -181,6 +160,5 @@ export function useContacts(opts: { apolloAuthReady: ComputedRef<boolean> }) {
     markAvatarBroken,
     contactInitials,
     refetchContacts,
-    refetchCommunications,
   };
 }