Fix workspace navigation regression on web (#772)

Centralize workspace navigation behind a small route-derived API so the workspace shell reads active selection from the current Expo Router route instead of a separately synchronized store.

Remove the stale layout-driven active-workspace write that regressed web after 02e5b564.

packages/app/src/keyboard/route-shortcut.test.ts

@@ -19,7 +19,6 @@ function makeCtx(overrides: Partial<ShortcutRoutingContext> = {}): ShortcutRouti
     isMobile: false,
     sidebarShortcutTargets: SIDEBAR_TARGETS,
     navigationActiveWorkspace: null,
-    lastNavigationWorkspaceRoute: null,
     commandCenterOpen: false,
     shortcutsDialogOpen: false,
     ...overrides,
@@ -253,39 +252,25 @@ describe("routeKeyboardShortcut — settings.toggle", () => {
     ).toEqual<ShortcutAction>({ kind: "router-push", route: "/settings" });
   });
 
-  it("replaces to the retained workspace route when leaving settings on desktop", () => {
+  it("navigates to the last workspace when leaving settings on desktop", () => {
     expect(
       routeKeyboardShortcut(
         { action: "settings.toggle", payload: null },
         makeCtx({
           pathname: "/settings/general",
           isMobile: false,
-          lastNavigationWorkspaceRoute: { serverId: "srv", workspaceId: "ws-2" },
         }),
       ),
-    ).toEqual<ShortcutAction>({
-      kind: "router-replace",
-      route: "/h/srv/workspace/ws-2",
-    });
+    ).toEqual<ShortcutAction>({ kind: "navigate-last-workspace" });
   });
 
-  it("falls back to router.back() when no retained workspace exists", () => {
-    expect(
-      routeKeyboardShortcut(
-        { action: "settings.toggle", payload: null },
-        makeCtx({ pathname: "/settings/general", lastNavigationWorkspaceRoute: null }),
-      ),
-    ).toEqual<ShortcutAction>({ kind: "router-back" });
-  });
-
-  it("falls back to router.back() on mobile even if a retained workspace exists", () => {
+  it("falls back to router.back() on mobile", () => {
     expect(
       routeKeyboardShortcut(
         { action: "settings.toggle", payload: null },
         makeCtx({
           pathname: "/settings/general",
           isMobile: true,
-          lastNavigationWorkspaceRoute: { serverId: "srv", workspaceId: "ws-2" },
         }),
       ),
     ).toEqual<ShortcutAction>({ kind: "router-back" });

packages/app/src/keyboard/route-shortcut.ts

@@ -1,10 +1,6 @@
 import type { KeyboardShortcutPayload, MessageInputKeyboardActionKind } from "@/keyboard/actions";
 import type { KeyboardActionDefinition } from "@/keyboard/keyboard-action-dispatcher";
-import {
-  buildHostWorkspaceRoute,
-  buildSettingsRoute,
-  parseHostWorkspaceRouteFromPathname,
-} from "@/utils/host-routes";
+import { buildSettingsRoute, parseHostWorkspaceRouteFromPathname } from "@/utils/host-routes";
 import {
   getRelativeSidebarShortcutTarget,
   type SidebarShortcutWorkspaceTarget,
@@ -15,7 +11,6 @@ export interface ShortcutRoutingContext {
   isMobile: boolean;
   sidebarShortcutTargets: ReadonlyArray<SidebarShortcutWorkspaceTarget>;
   navigationActiveWorkspace: SidebarShortcutWorkspaceTarget | null;
-  lastNavigationWorkspaceRoute: SidebarShortcutWorkspaceTarget | null;
   commandCenterOpen: boolean;
   shortcutsDialogOpen: boolean;
 }
@@ -35,6 +30,7 @@ export type ShortcutAction =
   | { kind: "none" }
   | { kind: "dispatch"; action: KeyboardActionDefinition }
   | { kind: "navigate-workspace"; serverId: string; workspaceId: string }
+  | { kind: "navigate-last-workspace" }
   | { kind: "router-replace"; route: string }
   | { kind: "router-back" }
   | { kind: "router-push"; route: string }
@@ -166,14 +162,8 @@ function routeSettingsToggle(ctx: ShortcutRoutingContext): ShortcutAction {
   if (!ctx.pathname.startsWith("/settings")) {
     return { kind: "router-push", route: buildSettingsRoute() };
   }
-  if (!ctx.isMobile && ctx.lastNavigationWorkspaceRoute) {
-    return {
-      kind: "router-replace",
-      route: buildHostWorkspaceRoute(
-        ctx.lastNavigationWorkspaceRoute.serverId,
-        ctx.lastNavigationWorkspaceRoute.workspaceId,
-      ),
-    };
+  if (!ctx.isMobile) {
+    return { kind: "navigate-last-workspace" };
   }
   return { kind: "router-back" };
 }