[Docs] Fixed broken links (#7091)

CORE-0000

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---

## PR-Codex overview
This PR primarily focuses on updating references from "backend wallets" to "server wallets" across various files and adding a new `ArticleCardIndex` component in the `page.tsx` file.

### Detailed summary
- In `sidebar.tsx`, updated `href` for the "Overview" link.
- Added a new `ArticleCardIndex` for "Universal Bridge" in `page.tsx`.
- Changed text from "backend wallets" to "server wallets" in `page.mdx`.
- Updated link in `engine-overview.tsx` to point to server wallet documentation.

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Author: saminacodes

apps/dashboard/src/app/(app)/team/[team_slug]/[project_slug]/engine/dedicated/(instance)/[engineId]/overview/components/engine-overview.tsx

@@ -95,12 +95,12 @@ function BackendWalletsSection(props: {
             </UnderlineLink>{" "}
             tab, or{" "}
             <TrackedUnderlineLink
-              href="https://portal.thirdweb.com/infrastructure/engine/features/backend-wallets"
+              href="https://portal.thirdweb.com/engine/v2/configure-wallets/server-wallet"
               target="_blank"
               label="learn-more"
               category="engine"
             >
-              learn more about backend wallets.
+              learn more about server wallets.
             </TrackedUnderlineLink>
           </p>
         </div>

apps/portal/src/app/engine/v2/get-started/page.mdx

@@ -96,10 +96,12 @@ Learn more about [admins](/engine/v2/features/admins) and [access tokens](/engin
 **Backend wallet** are your wallets managed by Engine. Engine will send blockchain transactions from these wallets.
 
 - Configure how to back up wallets.
-- Create or import a backend wallet.
-- Specify the backend wallet to use when calling the Engine API.
 
-[Learn more about backend wallets.](/engine/v2/features/backend-wallets)
+ - Create or import a server wallet.
+ - Specify the server wallet to use when calling the Engine API.
+
+
+[Learn more about server wallets.](/engine/v2/configure-wallets/server-wallet)
 
 ## Interact with the blockchain
 

apps/portal/src/app/page.tsx

@@ -154,6 +154,12 @@ function LearningResourcesSection() {
           description="Wallets, auth, and onchain interactions"
           icon={ConnectIcon}
         />
+        <ArticleCardIndex
+          href="/pay"
+          title="Universal Bridge"
+          description="Bridge and onramp tokens on any chain"
+          icon={BridgeIcon}
+        />
         <ArticleCardIndex
           href="/engine"
           title="Engine"

apps/portal/src/app/pay/sidebar.tsx

@@ -21,7 +21,7 @@ export const sidebar: SideBar = {
   links: [
     {
       name: "Overview",
-      href: `${paySlug}/overview`,
+      href: `${paySlug}`,
       icon: <WalletIcon />,
     },
     {