fix(app): stop spawning providers per client by warming the snapshot store

The workspace screen was prefetching per-provider model lists via
`useProviderModels`, which fanned out N parallel
`list_provider_models_request`s that bypassed `ProviderSnapshotManager`
and spawned each provider fresh on every call (e.g. repeated copilot
ENOENT errors). The return value was never consumed.

Replace it with `useProvidersSnapshot(serverId, workspaceDirectory)` so
warmup goes through the shared, deduped, TTL-cached snapshot path that
consumers already read from.

packages/app/src/hooks/use-provider-models.ts

@@ -1,49 +0,0 @@
-import { useMemo } from "react";
-import { useQueries } from "@tanstack/react-query";
-import {
-  AGENT_PROVIDER_DEFINITIONS,
-  type AgentProviderDefinition,
-} from "@server/server/agent/provider-manifest";
-import type { AgentModelDefinition, AgentProvider } from "@server/server/agent/agent-sdk-types";
-import { useHostRuntimeClient, useHostRuntimeIsConnected } from "@/runtime/host-runtime";
-
-const STALE_TIME = 5 * 60 * 1000;
-
-export function useProviderModels(serverId: string) {
-  const client = useHostRuntimeClient(serverId);
-  const isConnected = useHostRuntimeIsConnected(serverId);
-  const enabled = Boolean(serverId && client && isConnected);
-
-  const queries = useQueries({
-    queries: AGENT_PROVIDER_DEFINITIONS.map((def) => ({
-      queryKey: ["providerModels", serverId, def.id] as const,
-      enabled,
-      staleTime: STALE_TIME,
-      queryFn: async () => {
-        if (!client) {
-          throw new Error("Host is not connected");
-        }
-        const payload = await client.listProviderModels(def.id as AgentProvider);
-        if (payload.error) {
-          throw new Error(payload.error);
-        }
-        return payload.models ?? [];
-      },
-    })),
-  });
-
-  const allProviderModels = useMemo(() => {
-    const map = new Map<string, AgentModelDefinition[]>();
-    for (let i = 0; i < AGENT_PROVIDER_DEFINITIONS.length; i++) {
-      const query = queries[i];
-      if (query?.data) {
-        map.set(AGENT_PROVIDER_DEFINITIONS[i]!.id, query.data);
-      }
-    }
-    return map;
-  }, [queries]);
-
-  const isLoading = queries.some((q) => q.isLoading);
-
-  return { allProviderModels, isLoading };
-}