Fix TypeScript compilation errors and consolidate version handling

🤖 Generated with [opencode](https://opencode.ai)

Co-Authored-By: opencode <noreply@opencode.ai>

packages/opencode/src/installation/index.ts

@@ -2,10 +2,24 @@ import path from "path"
 import { $ } from "bun"
 import { z } from "zod"
 import { NamedError } from "../util/error"
+import { Bus } from "../bus"
+
+declare global {
+  const OPENCODE_VERSION: string
+}
 
 export namespace Installation {
   export type Method = Awaited<ReturnType<typeof method>>
 
+  export const Event = {
+    Updated: Bus.event(
+      "installation.updated",
+      z.object({
+        version: z.string(),
+      }),
+    ),
+  }
+
   export const Info = z
     .object({
       version: z.string(),