feat(accounts): add Aliases count column to Accounts and Groups

Same pattern as the existing quotaUsage deviation: neither list's
schema exposes an alias count as a column, only the full `aliases`
objectList on the detail view. Added a synthetic `aliasCount` column
(SCHEMA-DEVIATION: account-alias-count-column, documented in
SCHEMA_DEVIATIONS.md) that DynamicList resolves by fetching the real
`aliases` property and counting its entries.

Verified against a live test server: adding a real alias to an
account correctly bumps its Aliases count from 0 to 1 in the list.

src/lib/accountColumns.ts

@@ -19,6 +19,12 @@ import type { Schema } from '@/types/schema';
  * The Groups list gets the same `quotaUsage` column (groups have their own
  * `usedDiskQuota`/`quotas`, same as users), but not `roles` — that column
  * is specific to the Users list.
+ *
+ * SCHEMA-DEVIATION: account-alias-count-column (see SCHEMA_DEVIATIONS.md)
+ *
+ * Both lists also get a synthetic `aliasCount` column — DynamicList
+ * resolves it from the real `aliases` objectList property (an id-keyed
+ * map, per JMAP's objectList wire format) and renders its entry count.
  */
 export function withAccountListColumns(schema: Schema): Schema {
   let lists = schema.lists;
@@ -29,13 +35,18 @@ export function withAccountListColumns(schema: Schema): Schema {
       ...userList.columns.filter((c) => c.name !== 'createdAt'),
       { name: 'roles', label: 'Role' },
       { name: 'quotaUsage', label: 'Usage / Quota' },
+      { name: 'aliasCount', label: 'Aliases' },
     ];
     lists = { ...lists, 'x:Account/User': { ...userList, columns } };
   }
 
   const groupList = lists['x:Account/Group'];
   if (groupList) {
-    const columns = [...groupList.columns, { name: 'quotaUsage', label: 'Usage / Quota' }];
+    const columns = [
+      ...groupList.columns,
+      { name: 'quotaUsage', label: 'Usage / Quota' },
+      { name: 'aliasCount', label: 'Aliases' },
+    ];
     lists = { ...lists, 'x:Account/Group': { ...groupList, columns } };
   }