feat: implement new session behavior to clear selection and show empty state

- Added bilingual notes for the new session feature, detailing the transition to an empty state upon session creation.
- Updated `SessionsService` to include a `clear()` method that resets the current selection and persists the empty state.
- Enhanced the `EmptyState` component to reflect the new design, including workspace selection and input handling.
- Modified CSS styles for improved layout and visual consistency in the empty state.
- Updated tests to cover the new session clearing functionality and its effects on the UI.

packages/client/runtime/tests/sessions-service.spec.ts

@@ -133,6 +133,26 @@ describe('current selection (migrated from ui-layout, arbitrated into the list s
     expect(b.svc.list.getSnapshot().current).toBe('s1') // failed open leaves the selection alone
   })
 
+  it('clear() blanks list.current and the persisted selection', async () => {
+    const storage = new Map<string, string>()
+    vi.stubGlobal('localStorage', {
+      getItem: (k: string) => storage.get(k) ?? null,
+      setItem: (k: string, v: string) => { storage.set(k, v) },
+      removeItem: (k: string) => { storage.delete(k) },
+      clear: () => { storage.clear() },
+    })
+    const b = bench()
+    await feedList(b, [{ id: 's1' }])
+    b.svc.open(sid('s1'))
+    expect(storage.get('dsh.sessions.current')).toContain('s1')
+    b.svc.clear()
+    expect(b.svc.list.getSnapshot().current).toBeUndefined()
+    // Persisted wipe: a fresh service with the same storage stays on empty.
+    const again = bench()
+    await feedList(again, [{ id: 's1' }])
+    expect(again.svc.list.getSnapshot().current).toBeUndefined()
+  })
+
   it('masks (not destroys) the selection while its session is off the list', async () => {
     const b = bench()
     await feedList(b, [{ id: 's1' }, { id: 's2' }])