Keep workspaces responsive across app-wide routes (#2791)

* perf(app): retain inactive workspace screens

App-wide routes cleared the active workspace selection, which removed the retained workspace deck from the React tree and made returning rebuild every panel. Keep mounted deck entries inactive across those routes and suspend inactive panel subscriptions so state is preserved without background work.

* perf(app): suspend remaining inactive queries

Retained composers and commit diff panels still subscribed through query hooks that did not receive panel activity. Propagate the existing activity gate so app-wide routes leave those hidden surfaces dormant.

* refactor(app): separate panel activity from connectivity

A hidden retained panel is still connected to its host. Keep connectivity truthful, pause work inside query and stream owners, and preserve terminal emulator identity while its stream is detached.

* test(app): target active retained controls

* fix(app): retain compact and terminal route content

* fix(app): hide inactive workspace overlays

packages/app/src/git/use-diff-query.ts

@@ -1,4 +1,5 @@
 import { useMemo } from "react";
+import { useRetainedPanelActive } from "@/components/retained-panel";
 import { useReplicaQuery } from "@/data/query";
 import { checkoutDiffPushRoute } from "@/data/push-router";
 import { useHostRuntimeIsConnected } from "@/runtime/host-runtime";
@@ -47,6 +48,8 @@ export function useCheckoutDiffQuery({
   enabled = true,
   queryScope,
 }: UseCheckoutDiffQueryOptions) {
+  const retainedPanelActive = useRetainedPanelActive();
+  const queryEnabled = enabled && retainedPanelActive;
   const isConnected = useHostRuntimeIsConnected(serverId);
   const normalizedCompare = useMemo(
     () => normalizeCheckoutDiffCompare({ mode, baseRef, ignoreWhitespace }),
@@ -67,7 +70,7 @@ export function useCheckoutDiffQuery({
     return normalizedScope ? [...comparisonKey, "scope", normalizedScope] : comparisonKey;
   }, [serverId, cwd, compareMode, compareBaseRef, compareIgnoreWhitespace, queryScope]);
   const subscriptionId = useMemo(() => `checkoutDiff:${JSON.stringify(queryKey)}`, [queryKey]);
-  const routeEnabled = Boolean(enabled && isConnected && cwd);
+  const routeEnabled = Boolean(queryEnabled && isConnected && cwd);
 
   const query = useReplicaQuery<CheckoutDiffQueryPayload>({
     queryKey,
@@ -93,7 +96,7 @@ export function useCheckoutDiffQuery({
     files: payload?.files ?? [],
     payloadError,
     diffTooLarge: payload?.diffTooLarge === true,
-    isLoading: payload === null && enabled && isConnected,
+    isLoading: payload === null && queryEnabled && isConnected,
     isFetching: false,
     isError: Boolean(payloadError),
     error: null,