Merge sidebar workspaces across all connected hosts (#1538)

* Merge workspaces across all hosts in the sidebar

Replace per-host sidebar sections with a single merged project list.
Projects that exist on multiple hosts (matched by projectKey) are
collapsed into one row. Host identity is surfaced via:

- A status-only footer pill showing online/offline host counts
- Hover cards with a mandatory host row on every workspace entry
- Subtitles showing the host name when a project spans >1 host
- A host filter in the grouping dropdown (not a sidebar switcher)

Order and group-mode stores migrated from per-server to global keys
with zustand persist migrations. New-workspace screen now shows a
merged project list with a host selector combobox.

Key files:
- workspace-structure.ts: merge algorithm by projectKey
- sidebar-view-store.ts / sidebar-order-store.ts: global state
- sidebar-workspace-list.tsx: context-based subtitle injection
- new-workspace-screen.tsx: host selector in footer row

* Add host filtering to the merged sidebar

The sidebar now merges workspaces from every connected host, so a single
global "active host" no longer fits. Host selection becomes explicit per
action via a host chooser, and agent history pages across all hosts at
once. Removes the active-host / active-server-id model and the
all-agents-list hook that fed it.

* Fix rebase fallout: translate archive host error, update stale workspace-key test

archiveWorkspacesOptimistically used a raw "Host is not connected" string
that the i18n completeness test forbids; route it through i18n.t with the
existing hostDisconnected key. The selectors memoization test asserted
un-prefixed workspace keys, but merged-sidebar keys are serverId-prefixed.

* Fix sidebar review fallout

* Address sidebar review followups

* Fix sidebar workspace identity migration

* Address sidebar review followups

* Handle partial host history failures

* Fix merged sidebar project removal and E2E drift

* Restore history routes and project removal shape

* Remove sidebar host context plumbing

* Tighten sidebar status and host filter state

* Keep new workspace project selection host-compatible

* Migrate sidebar view storage

* Streamline host selection flows

* Update all-host history on archive

* Fix empty project sidebar action

Code regression: the main merge dropped the empty-project New workspace child row while keeping the empty project persistence contract. Restore the row using the project host target so the sidebar stays aligned with the no-host-selection model.

* Fix Japanese shortcut translation key

Stale-base integration: main added the Japanese locale after this branch added cycleAgentMode to the English shortcut help map. Merging main exposed the missing ja key in CI typecheck and resources.test.

* Fix Playwright speech teardown race

packages/app/src/utils/sidebar-project-row-model.ts

@@ -1,13 +1,63 @@
 import type { SidebarProjectEntry } from "@/hooks/use-sidebar-workspaces-list";
 
+export interface SidebarProjectHostTarget {
+  serverId: string;
+  iconWorkingDir: string;
+}
+
+export type SidebarProjectTrailingAction =
+  | { kind: "new_worktree"; target: SidebarProjectHostTarget }
+  | { kind: "none" };
+
 export interface SidebarProjectSectionRowModel {
   kind: "project_section";
   chevron: "expand" | "collapse";
-  trailingAction: "new_worktree" | "none";
+  trailingAction: SidebarProjectTrailingAction;
 }
 
 export type SidebarProjectRowModel = SidebarProjectSectionRowModel;
 
+function hostTarget(input: {
+  serverId: string;
+  iconWorkingDir: string;
+}): SidebarProjectHostTarget | null {
+  const iconWorkingDir = input.iconWorkingDir.trim();
+  if (!input.serverId || !iconWorkingDir) {
+    return null;
+  }
+  return { serverId: input.serverId, iconWorkingDir };
+}
+
+export function resolveSidebarProjectIconTarget(
+  project: SidebarProjectEntry,
+): SidebarProjectHostTarget | null {
+  for (const host of project.hosts) {
+    const target = hostTarget(host);
+    if (target) {
+      return target;
+    }
+  }
+  return null;
+}
+
+function resolveNewWorktreeTarget(project: SidebarProjectEntry): SidebarProjectHostTarget | null {
+  for (const host of project.hosts) {
+    if (!host.canCreateWorktree) {
+      continue;
+    }
+    const target = hostTarget(host);
+    if (target) {
+      return target;
+    }
+  }
+  return null;
+}
+
+function projectTrailingAction(project: SidebarProjectEntry): SidebarProjectTrailingAction {
+  const target = resolveNewWorktreeTarget(project);
+  return target ? { kind: "new_worktree", target } : { kind: "none" };
+}
+
 export function buildSidebarProjectRowModel(input: {
   project: SidebarProjectEntry;
   collapsed: boolean;
@@ -15,6 +65,6 @@ export function buildSidebarProjectRowModel(input: {
   return {
     kind: "project_section",
     chevron: input.collapsed ? "expand" : "collapse",
-    trailingAction: input.project.canCreateWorktree ? "new_worktree" : "none",
+    trailingAction: projectTrailingAction(input.project),
   };
 }