fix(evm-explorer): clear stale result on network switch; surface explorer on EVM home

Addresses Monty's review feedback on #30:

- Reset requestResult whenever the active endpoint changes (network
  segment switch or custom-URL edit) so a response from one endpoint is
  never left showing under a different network's label.
- Promote the JSON-RPC explorer on the EVM home page: add a "JSON-RPC
  Explorer" card to Development Tools and replace the buried trailing
  text link in RPC Endpoints with a prominent card.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: alexander-sei

evm/index.mdx

@@ -52,13 +52,16 @@ keywords: ["sei evm", "ethereum virtual machine", "web3 development", "blockchai
 
 ## Development Tools
 
-<CardGroup cols={2}>
+<CardGroup cols={3}>
   <Card horizontal title="Deploy with Hardhat" icon="terminal" href="/evm/evm-hardhat">
     Deploy smart contracts on Sei EVM using Hardhat. Simple setup, fast results.
   </Card>
   <Card horizontal title="Deploy with Foundry" icon="cube" href="/evm/evm-foundry">
     Use Foundry to build and deploy on Sei EVM. Fast testing, simple deployment.
   </Card>
+  <Card horizontal title="JSON-RPC Explorer" icon="compass" href="/evm/reference">
+    Browse every Sei EVM JSON-RPC method, run live requests, and copy ready-to-use code.
+  </Card>
 </CardGroup>
 
 ## Use Cases
@@ -96,4 +99,6 @@ Choose from official Sei Foundation endpoints or community-maintained alternativ
   </Tab>
 </Tabs>
 
-For the complete list of JSON-RPC methods, see the [EVM reference](/evm/reference).
+<Card horizontal title="Interactive JSON-RPC Explorer" icon="code" href="/evm/reference">
+  Search every Sei EVM JSON-RPC method with Sei-specific behavior notes, switch between mainnet, testnet, and custom endpoints, run live requests, and generate ready-to-use client code.
+</Card>

snippets/rpc-methods-viewer.jsx

@@ -295,6 +295,11 @@ const isMutation = (name) => name === 'eth_sendRawTransaction' || name === 'eth_
 
   useEffect(() => { if (consoleActive) validateEndpoint(); }, [validateEndpoint, consoleActive]);
 
+  // Clear any prior run result when the target endpoint changes (network switch
+  // or custom-URL edit), so a response from one endpoint is never left showing
+  // under a different network's label.
+  useEffect(() => { setRequestResult(null); }, [endpoint]);
+
   const allMethods = useMemo(() => SEI_RPC_METHODS.map((m) => ({ ...m, meta: NAMESPACE_META[m.namespace] || { label: m.namespace, color: '#6b7280' } })), []);
 
   const filteredMethods = useMemo(() => {