opencode: provide channel to web build (#28612)

packages/app/vite.js

@@ -5,6 +5,13 @@ import { fileURLToPath } from "url"
 
 const theme = fileURLToPath(new URL("./public/oc-theme-preload.js", import.meta.url))
 
+const channel = (() => {
+  const raw = process.env.OPENCODE_CHANNEL
+  if (raw === "dev" || raw === "beta" || raw === "prod") return raw
+  if (process.env.OPENCODE_CHANNEL === "latest") return "prod"
+  return "dev"
+})()
+
 /**
  * @type {import("vite").PluginOption}
  */
@@ -18,6 +25,9 @@ export default [
             "@": fileURLToPath(new URL("./src", import.meta.url)),
           },
         },
+        define: {
+          "import.meta.env.VITE_OPENCODE_CHANNEL": JSON.stringify(channel),
+        },
         worker: {
           format: "es",
         },