feat: handling subscription tier button link parameter (#7553)

## Summary

Discussion here:
https://comfy-organization.slack.com/archives/C0A0XANFJRE/p1764899027465379

Implement: Subscription tier query parameter for direct checkout flow

Example button link: `/cloud/subscribe?tier=standard`

`tier` could be `standard`, `creator` or `pro`
`cycle` could be `monthly` or `yearly`. it is optional, and `monthly` by
default.

<!-- One sentence describing what changed and why. -->

## Changes

- **What**: <!-- Core functionality added/modified -->
- Add a landing page called `CloudSubscriptionRedirectView.vue` to
handling the subscription tier button link parameter
  - Extract subscription handling logic from `PriceTable.vue`
 
- **Breaking**: <!-- Any breaking changes (if none, remove this line)
-->
  - Code change touched  `PriceTable.vue`
- **Dependencies**: <!-- New dependencies (if none, remove this line)
-->

## Review Focus
- link will redirect to login url, when cloud app not login
- after login, the cloud app will redirect to CloudSubscriptionRedirect
page
- wait for several seconds, the cloud app will be redirected to checkout
page

<!-- Critical design decisions or edge cases that need attention -->

<!-- If this PR fixes an issue, uncomment and update the line below -->
<!-- Fixes #ISSUE_NUMBER -->

## Screenshots (if applicable)

![Kapture 2025-12-16 at 18 43
28](https://github.com/user-attachments/assets/affbc18f-d45c-4953-b06a-fc797eba6804)


<!-- Add screenshots or video recording to help explain your changes -->

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7553-feat-handling-subscription-tier-button-link-parameter-2cb6d73d365081ee9580e89090248300)
by [Unito](https://www.unito.io)

---------

Co-authored-by: GitHub Action <action@github.com>

src/router.ts

@@ -149,9 +149,17 @@ if (isCloud) {
       return next()
     }
 
+    const query =
+      to.fullPath === '/'
+        ? undefined
+        : { previousFullPath: encodeURIComponent(to.fullPath) }
+
     // Check if route requires authentication
     if (to.meta.requiresAuth && !isLoggedIn) {
-      return next({ name: 'cloud-login' })
+      return next({
+        name: 'cloud-login',
+        query
+      })
     }
 
     // Handle other protected routes
@@ -164,7 +172,10 @@ if (isCloud) {
       }
 
       // For web, redirect to login
-      return next({ name: 'cloud-login' })
+      return next({
+        name: 'cloud-login',
+        query
+      })
     }
 
     // User is logged in - check if they need onboarding (when enabled)