style: update ui and design of system notification components (what's new, new release notification, help center) (#6300)

## Summary

Migrated help center and release notification components from hardcoded
colors to semantic design tokens for automatic light/dark theme support.

<img width="808" height="874" alt="Selection_2298"
src="https://github.com/user-attachments/assets/c7fb956e-700b-49df-bba0-b85705e89ce7"
/>

<img width="852" height="710" alt="Selection_2265"
src="https://github.com/user-attachments/assets/618205e1-5068-499d-80ab-72626b32d7e1"
/>

<img width="493" height="838" alt="Screenshot from 2025-10-25 21-46-11"
src="https://github.com/user-attachments/assets/7b696673-ec19-4a16-a0b5-ca744ae62fe1"
/>

<img width="493" height="838" alt="Screenshot from 2025-10-25 21-46-25"
src="https://github.com/user-attachments/assets/2767d722-a0e1-426d-82d9-6d5a59f373ee"
/>

## Changes

- **What**: Replaced hardcoded hex/rgb colors with semantic tokens in
HelpCenterMenuContent, WhatsNewPopup, and ReleaseNotificationToast
components
- **Design System**: Added `--interface-menu-surface` and
`--interface-menu-stroke` tokens to style.css for consistent menu
theming
- **UX**: Updated help center menu structure - added "Give Feedback"
button, renamed "Help & Feedback" to "Help & Support", switched to
Lucide icons (except Discord brand logo), added external-link icons

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6300-style-update-ui-and-design-of-system-notification-components-what-s-new-new-release-no-2986d73d365081238458ea7d304b641e)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Alexander Brown <drjkl@comfy.org>

browser_tests/tests/releaseNotifications.spec.ts

@@ -50,7 +50,7 @@ test.describe('Release Notifications', () => {
     await expect(helpMenu).toBeVisible()
 
     // Verify "What's New?" section shows the release
-    const whatsNewSection = comfyPage.page.locator('.whats-new-section')
+    const whatsNewSection = comfyPage.page.getByTestId('whats-new-section')
     await expect(whatsNewSection).toBeVisible()
 
     // Should show the release version
@@ -79,7 +79,7 @@ test.describe('Release Notifications', () => {
     await expect(helpMenu).toBeVisible()
 
     // Verify "What's New?" section shows no releases
-    const whatsNewSection = comfyPage.page.locator('.whats-new-section')
+    const whatsNewSection = comfyPage.page.getByTestId('whats-new-section')
     await expect(whatsNewSection).toBeVisible()
 
     // Should show "No recent releases" message
@@ -125,7 +125,7 @@ test.describe('Release Notifications', () => {
     await expect(helpMenu).toBeVisible()
 
     // Should show no releases due to error
-    const whatsNewSection = comfyPage.page.locator('.whats-new-section')
+    const whatsNewSection = comfyPage.page.getByTestId('whats-new-section')
     await expect(
       whatsNewSection.locator('text=No recent releases')
     ).toBeVisible()
@@ -175,7 +175,7 @@ test.describe('Release Notifications', () => {
     await expect(helpMenu).toBeVisible()
 
     // Verify "What's New?" section is hidden
-    const whatsNewSection = comfyPage.page.locator('.whats-new-section')
+    const whatsNewSection = comfyPage.page.getByTestId('whats-new-section')
     await expect(whatsNewSection).not.toBeVisible()
 
     // Should not show any popups or toasts
@@ -260,7 +260,7 @@ test.describe('Release Notifications', () => {
     await expect(helpMenu).toBeVisible()
 
     // Verify "What's New?" section is visible
-    const whatsNewSection = comfyPage.page.locator('.whats-new-section')
+    const whatsNewSection = comfyPage.page.getByTestId('whats-new-section')
     await expect(whatsNewSection).toBeVisible()
 
     // Should show the release
@@ -308,7 +308,7 @@ test.describe('Release Notifications', () => {
     await helpCenterButton.click()
 
     // Verify "What's New?" section is visible
-    const whatsNewSection = comfyPage.page.locator('.whats-new-section')
+    const whatsNewSection = comfyPage.page.getByTestId('whats-new-section')
     await expect(whatsNewSection).toBeVisible()
 
     // Close help center
@@ -359,7 +359,7 @@ test.describe('Release Notifications', () => {
     await expect(helpMenu).toBeVisible()
 
     // Section should be hidden regardless of empty releases
-    const whatsNewSection = comfyPage.page.locator('.whats-new-section')
+    const whatsNewSection = comfyPage.page.getByTestId('whats-new-section')
     await expect(whatsNewSection).not.toBeVisible()
   })
 })