ui(pool): pick an account's users from its own Edit

Each account row in the Account pool card has a pencil: tick the users
whose sessions run on it (one moves off any other account, unticking sends
one back to the balancer). PUT /api/accounts/:name/users saves the set in one
transaction, audits each change and switches a Claude login into each added
user's home at once. The card-level switch button and pinned list are gone.

client/src/lib/api.ts

@@ -1061,15 +1061,19 @@ export const api = {
         method: "POST",
         body: JSON.stringify({ ...body, currentPassword }),
       }),
-    /** PUT /api/accounts/pins — admin: switch a user to one account (`null` = automatic), password again. */
-    pin: (tool: PoolTool, userId: number, account: string | null, currentPassword: string) =>
+    /** PUT /api/accounts/:name/users — admin: exactly these users run on this account. */
+    setUsers: (tool: PoolTool, name: string, userIds: number[], currentPassword: string) =>
       request<{
-        pin: { userId: number; username: string; account: string | null };
-        /** What happened now: a Claude login goes into the user's home at once. */
-        switched: "switched" | "kept" | "own-login" | "expired" | "next-session" | null;
-      }>("/accounts/pins", {
+        /** Users moved onto it; `switched`: what happened now (a Claude login goes into their home). */
+        added: {
+          userId: number;
+          username: string;
+          switched: "switched" | "kept" | "own-login" | "expired" | "next-session";
+        }[];
+        removed: { userId: number; username: string }[];
+      }>(`/accounts/${encodeURIComponent(name)}/users`, {
         method: "PUT",
-        body: JSON.stringify({ tool, userId, account, currentPassword }),
+        body: JSON.stringify({ tool, userIds, currentPassword }),
       }),
     /** DELETE /api/accounts/:name — admin, with their OWN password again. */
     remove: (tool: PoolTool, name: string, currentPassword: string) =>