fix(opencode): pass `EXA_API_KEY` to `websearch` tool to avoid rate limits (#16362)

Co-authored-by: Dax Raad <d@ironbay.co>
Co-authored-by: Aiden Cline <aidenpcline@gmail.com>
Co-authored-by: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>

packages/opencode/src/tool/mcp-exa.ts

@@ -1,7 +1,9 @@
 import { Duration, Effect, Schema } from "effect"
 import { HttpClient, HttpClientRequest } from "effect/unstable/http"
 
-const URL = "https://mcp.exa.ai/mcp"
+const URL = process.env.EXA_API_KEY
+  ? `https://mcp.exa.ai/mcp?exaApiKey=${encodeURIComponent(process.env.EXA_API_KEY)}`
+  : "https://mcp.exa.ai/mcp"
 
 const McpResult = Schema.Struct({
   result: Schema.Struct({