fix(auto-updater): handle bun.lockb and add workspace validation

- Support binary bun.lockb format by deleting entire file (cannot parse)
- Add workspace check: verify package.json exists before bun install
- Quote paths in error messages for Windows/paths with spaces

src/cli/config-manager/bun-install.test.ts

@@ -1,4 +1,5 @@
-import { beforeEach, afterEach, describe, expect, it, mock, spyOn } from "bun:test"
+import { beforeEach, afterEach, describe, expect, it, spyOn } from "bun:test"
+import * as fs from "node:fs"
 import * as dataPath from "../../shared/data-path"
 import * as logger from "../../shared/logger"
 import * as spawnHelpers from "../../shared/spawn-with-windows-hide"
@@ -8,6 +9,7 @@ describe("runBunInstallWithDetails", () => {
   let getOpenCodeCacheDirSpy: ReturnType<typeof spyOn>
   let logSpy: ReturnType<typeof spyOn>
   let spawnWithWindowsHideSpy: ReturnType<typeof spyOn>
+  let existsSyncSpy: ReturnType<typeof spyOn>
 
   beforeEach(() => {
     getOpenCodeCacheDirSpy = spyOn(dataPath, "getOpenCodeCacheDir").mockReturnValue("/tmp/opencode-cache")
@@ -15,14 +17,16 @@ describe("runBunInstallWithDetails", () => {
     spawnWithWindowsHideSpy = spyOn(spawnHelpers, "spawnWithWindowsHide").mockReturnValue({
       exited: Promise.resolve(0),
       exitCode: 0,
-      kill: mock(() => {}),
+      kill: () => {},
     } as ReturnType<typeof spawnHelpers.spawnWithWindowsHide>)
+    existsSyncSpy = spyOn(fs, "existsSync").mockReturnValue(true)
   })
 
   afterEach(() => {
     getOpenCodeCacheDirSpy.mockRestore()
     logSpy.mockRestore()
     spawnWithWindowsHideSpy.mockRestore()
+    existsSyncSpy.mockRestore()
   })
 
   it("runs bun install in the OpenCode cache directory", async () => {