feat(app): sidebar reveal animation, hover peek overlay, and weaker dividers (#16374)

Co-authored-by: Adam <2363879+adamdotdevin@users.noreply.github.com>

packages/app/e2e/sidebar/sidebar-popover-actions.spec.ts

@@ -1,6 +1,6 @@
 import { test, expect } from "../fixtures"
 import { closeSidebar, hoverSessionItem } from "../actions"
-import { projectSwitchSelector, sessionItemSelector } from "../selectors"
+import { projectSwitchSelector } from "../selectors"
 
 test("collapsed sidebar popover stays open when archiving a session", async ({ page, slug, sdk, gotoSession }) => {
   const stamp = Date.now()
@@ -15,12 +15,15 @@ test("collapsed sidebar popover stays open when archiving a session", async ({ p
     await gotoSession(one.id)
     await closeSidebar(page)
 
+    const oneItem = page.locator(`[data-session-id="${one.id}"]`).last()
+    const twoItem = page.locator(`[data-session-id="${two.id}"]`).last()
+
     const project = page.locator(projectSwitchSelector(slug)).first()
     await expect(project).toBeVisible()
     await project.hover()
 
-    await expect(page.locator(sessionItemSelector(one.id)).first()).toBeVisible()
-    await expect(page.locator(sessionItemSelector(two.id)).first()).toBeVisible()
+    await expect(oneItem).toBeVisible()
+    await expect(twoItem).toBeVisible()
 
     const item = await hoverSessionItem(page, one.id)
     await item
@@ -28,7 +31,7 @@ test("collapsed sidebar popover stays open when archiving a session", async ({ p
       .first()
       .click()
 
-    await expect(page.locator(sessionItemSelector(two.id)).first()).toBeVisible()
+    await expect(twoItem).toBeVisible()
   } finally {
     await sdk.session.delete({ sessionID: one.id }).catch(() => undefined)
     await sdk.session.delete({ sessionID: two.id }).catch(() => undefined)