test(web): lifecycle & chrome scenarios — workspace flow, reload recovery, dark mode

One tiny recorded text turn drives three whole-page concerns:

- workspace flow over the real wire: the empty-state hero's first send
  materializes a real Workspace + Session (the jsdom workspace-flow suite
  pins this state machine over the fixture client; this scenario pins it
  through HTTP RPC + SSE + the gateway). Durable proof: the session
  header's cwd is the create-by-name target <workspaceRoot>/workspace.
  Adds the hero waiting-state aria golden.
- reload recovery: collapse the sidebar (persisted dsh.layout.panels),
  page.reload, and the surface comes back whole from persistence alone —
  layout collapsed, selection restored (dsh.sessions.current), the
  recorded turn re-rendered from session.history with zero model calls
  (the drained replay cursor makes any stray request fail loud at close).
- dark mode: no product control flips the theme yet, so the scenario
  drives the ThemeService's entire DOM contract — body[data-ds-dark-theme]
  — and pins the shipped cascade: the alias token flips, a painted surface
  repaints, and removing the attribute restores the light sample exactly.
  TODO(web-theme-gesture) upgrades to a real settings control; no theme
  golden per the lane's scope ruling (aria is color-blind).

Agent Note scenario list extended in both languages; pairing re-recorded.

apps/web/tests/snapshots/lifecycle-chrome/hero.expected.md

@@ -0,0 +1,35 @@
+- button "Collapse sidebar":
+  - img
+- button "New session":
+  - img
+  - text: New Session
+- text: Workspaces
+- button "Group by":
+  - img
+- button "Create workspace":
+  - img
+- button "Search sessions":
+  - img
+- textbox "Search name, keywords..."
+- tree "Sessions": No sessions yet
+- button "Settings":
+  - img
+  - text: Settings
+- text: Let's start building
+- button "Choose workspace":
+  - img
+  - text: workspace
+  - img
+- textbox "Describe what you want to build"
+- button "Add attachment":
+  - img
+- combobox "Plan mode":
+  - option "Plan" [selected]
+  - option "Agent"
+- combobox "Access mode":
+  - option "Read-only" [selected]
+  - option "Read-write"
+- combobox "Model":
+  - option "DeepSeek-V4-Pro High" [selected]
+  - option "DeepSeek-V4-Pro"
+- button "Send message" [disabled]