feat(web): session list one-list, hover card, row menus, rename, manual ordering

Sidebar session list grows the figma 239-10458 feature set and the
workspace/session browsing region moves wholesale into ui-workspace:

- Group-by menu (WorkSpace / In one list): flat mode lists every session
  top-level, strictly newest-first; the choice persists across reloads.
- Session rows get a 500ms hover detail card (title / relative time /
  status line) and a ... menu (Rename / Fork session / Delete session,
  visual-only for now); workspace headers get ... with Rename (wired) and
  Delete workspace (visual-only).
- workspace.rename RPC: trims, rejects duplicate titles on the create
  chain (workspace-name-conflict), no-op on same title; modal dialog with
  client-side duplicate pre-check.
- workspace.insertSessionBefore RPC (DOM-insertBefore semantics, omitted
  anchor appends): HTML5 drag reorder of root sessions inside a workspace
  group; order truth stays host-side, the view refreshes from the
  response/changed frame.
- Activity pinning removed: the session/event touchSession chain is gone;
  workspace accounts are manually owned (new sessions prepend, explicit
  reordering only). Contracts and tests updated, api catalog regenerated.
- ui-sidebar reduced to the column shell (brand, fold state machine, New
  Session, Settings) exposing one sidebar.workspaces hole with a two-fact
  owner share {wide, expandSidebar}; ui-workspace owns the whole region
  (header, search, grouped/flat lists, dialogs, drag) plus the picker via
  a shared WorkspaceCreateFlow. The old sidebar.workspace picker slot and
  its deferral indirection are gone.
- ui-primitives: Menu gains label entries, danger rows, and
  closeOnPointerLeave; new HoverCard (portaled, open-delay, disabled
  guard). Hover card and row menu never coexist.

packages/client/ui-sidebar/tests/apply.spec.tsx

@@ -1,4 +1,4 @@
-/** Sidebar slot registration and its plain runtime/layout callbacks. */
+/** Sidebar shell slot registration and its plain runtime/layout callbacks. */
 import { Context } from 'cordis'
 import { describe, expect, it, vi } from 'vitest'
 import { SlotsService } from '@deepseek-ai/dsh-client-runtime/client'
@@ -9,10 +9,8 @@ async function bench(declare = true) {
   const ctx = new Context()
   await ctx.plugin(SlotsService).await()
   const layout = { toggleSidebar: vi.fn() }
-  const sessions = { open: vi.fn() }
   const workspaces = { startSession: vi.fn() }
   ctx.provide('layout', layout)
-  ctx.provide('sessions', sessions as never)
   ctx.provide('workspaces', workspaces as never)
   const slots = ctx.get('slots') as SlotsService
   if (declare) {
@@ -21,25 +19,23 @@ async function bench(declare = true) {
       () => null,
     )
   }
-  return { ctx, slots, layout, sessions, workspaces }
+  return { ctx, slots, layout, workspaces }
 }
 
 describe('ui-sidebar apply', () => {
   it('declares only the services it uses', () => {
-    expect(inject).toEqual(['slots', 'layout', 'sessions', 'workspaces'])
+    expect(inject).toEqual(['slots', 'layout', 'workspaces'])
   })
 
-  it('registers the sidebar and declares its Workspace picker hole', async () => {
+  it('registers the shell and declares the browsing-region hole', async () => {
     const b = await bench()
     await b.ctx.plugin({ inject: [...inject], apply }).await()
     expect(b.slots.entries('sidebar')).toHaveLength(1)
-    expect(b.slots.spec('sidebar.workspace')).toEqual({ kind: 'single', scope: 'root' })
+    expect(b.slots.spec('sidebar.workspaces')).toEqual({ kind: 'single', scope: 'root' })
     const injected = (b.slots.entries('sidebar')[0]!.inject as () => SidebarRootInjected)()
-    expect(Object.keys(injected)).toEqual(['startSession', 'open', 'toggleSidebar'])
+    expect(Object.keys(injected)).toEqual(['startSession', 'toggleSidebar'])
     injected.startSession('workspace' as never, 'prompt')
     expect(b.workspaces.startSession).toHaveBeenCalledWith('workspace', 'prompt')
-    injected.open('session' as never)
-    expect(b.sessions.open).toHaveBeenCalledWith('session')
     injected.toggleSidebar()
     expect(b.layout.toggleSidebar).toHaveBeenCalledOnce()
   })
@@ -55,6 +51,6 @@ describe('ui-sidebar apply', () => {
     await fiber.await()
     await fiber.dispose()
     expect(b.slots.entries('sidebar')).toHaveLength(0)
-    expect(b.slots.spec('sidebar.workspace')).toBeUndefined()
+    expect(b.slots.spec('sidebar.workspaces')).toBeUndefined()
   })
 })