Fix broken card links on Node API Overview page (#992)

The WebSockets, Debug API, and Yellowstone gRPC cards used relative
hrefs that didn't resolve correctly. Updated them to absolute paths
matching each page's frontmatter slug.

Co-authored-by: dslovinsky <dslovinsky@users.noreply.github.com>

Author: dslovinsky

fern/api-reference/node-api/node-api-overview.mdx

@@ -41,19 +41,19 @@ Chain APIs are the per-chain RPC surfaces exposed through the Node API.
 Use these alongside the Node API for streaming, performance, and deeper inspection. Chain coverage varies: check each page for supported networks.
 
 <CardGroup>
-  <Card title="WebSockets" icon="fa-solid fa-wave-square" href="subscription-api">
+  <Card title="WebSockets" icon="fa-solid fa-wave-square" href="/reference/subscription-api">
     Subscribe to pending transactions, log events, new blocks, and more.
   </Card>
 
   <Card title="Trace API" icon="fa-solid fa-magnifying-glass-arrow-right" href="/reference/transfers-api-quickstart">
     Get insights into transaction processing and onchain activity.
   </Card>
 
-  <Card title="Debug API" icon="fa-solid fa-bug" href="debug-api-quickstart">
+  <Card title="Debug API" icon="fa-solid fa-bug" href="/reference/debug-api-quickstart">
     Non-standard RPC methods for inspecting and debugging transactions.
   </Card>
 
-  <Card title="Yellowstone gRPC" icon="fa-solid fa-bolt" href="yellowstone-grpc-overview">
+  <Card title="Yellowstone gRPC" icon="fa-solid fa-bolt" href="/reference/yellowstone-grpc-overview">
     High-performance real-time Solana data streaming interface.
   </Card>
 </CardGroup>