fix(app): preserve todo dock across sessions

packages/app/test-browser/motion-spring.test.ts

@@ -0,0 +1,21 @@
+import { expect, test } from "bun:test"
+import { useSpring } from "@opencode-ai/ui/motion-spring"
+import { createRoot, createSignal } from "solid-js"
+
+test("snaps spring progress when the session changes", async () => {
+  const state = createRoot((dispose) => {
+    const [target, setTarget] = createSignal(0)
+    const [session, setSession] = createSignal("session-a")
+    const progress = useSpring(target, { visualDuration: 0.3, bounce: 0 }, session)
+    return { dispose, progress, setTarget, setSession }
+  })
+
+  await new Promise<void>(queueMicrotask)
+  state.setTarget(1)
+  expect(state.progress()).toBe(0)
+
+  state.setSession("session-b")
+  await Bun.sleep(0)
+  expect(state.progress()).toBe(1)
+  state.dispose()
+})