chore: add OPENCODE env var (#1780)

packages/opencode/src/index.ts

@@ -58,6 +58,8 @@ const cli = yargs(hideBin(process.argv))
       })(),
     })
 
+    process.env["OPENCODE"] = "1"
+
     Log.Default.info("opencode", {
       version: Installation.VERSION,
       args: process.argv.slice(2),