ui: add Radix tooltips to header icons

ui/e2e/tooltip.spec.ts

@@ -0,0 +1,47 @@
+import { test, expect } from '@playwright/test'
+
+/**
+ * E2E tooltip tests for header icon buttons.
+ *
+ * Run tests:
+ *   cd ui && npm run test:e2e
+ *   cd ui && npm run test:e2e -- tooltip.spec.ts
+ */
+test.describe('Header tooltips', () => {
+  test.setTimeout(30000)
+
+  test.beforeEach(async ({ page }) => {
+    await page.goto('/')
+    await page.waitForSelector('button:has-text("Select Project")', { timeout: 10000 })
+  })
+
+  async function selectProject(page: import('@playwright/test').Page) {
+    const projectSelector = page.locator('button:has-text("Select Project")')
+    if (await projectSelector.isVisible()) {
+      await projectSelector.click()
+      const items = page.locator('.neo-dropdown-item')
+      const itemCount = await items.count()
+      if (itemCount === 0) return false
+      await items.first().click()
+      await expect(projectSelector).not.toBeVisible({ timeout: 5000 }).catch(() => {})
+      return true
+    }
+    return false
+  }
+
+  test('Settings tooltip shows on hover', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    const settingsButton = page.locator('button[aria-label="Open Settings"]')
+    await expect(settingsButton).toBeVisible()
+
+    await settingsButton.hover()
+
+    const tooltip = page.locator('[data-slot="tooltip-content"]', { hasText: 'Settings' })
+    await expect(tooltip).toBeVisible({ timeout: 2000 })
+  })
+})