fix(cli): resolve Windows CI test failures across three platform issues

- Use Bun.which() with process.execPath fallback in run-cli helper to
  resolve bun executable on Windows (fixes 22 integration tests)
- Normalize paths in credentials-store test for Windows backslash compat
- Use shell: true on Windows in updater spawn for proper exe resolution

cli/src/platform/updater.ts

@@ -1,4 +1,5 @@
 import { spawn } from 'node:child_process'
+import type { ChildProcess, SpawnOptions } from 'node:child_process'
 
 export interface UpdaterRunResult {
   success: boolean
@@ -15,18 +16,22 @@ export async function runUpdateCommand(command: string): Promise<UpdaterRunResul
     if (!program) {
       return { success: false, output: 'empty update command' }
     }
-    const executable = process.platform === 'win32' && !program.endsWith('.cmd') && !program.endsWith('.exe')
-      ? `${program}.cmd`
-      : program
+
+    // On Windows, use shell: true to let the OS resolve the executable
+    // This handles both .exe and .cmd extensions automatically
+    const spawnOptions: SpawnOptions = {
+      stdio: ['ignore', 'pipe', 'pipe'],
+      ...(process.platform === 'win32' && { shell: true })
+    }
 
     return await new Promise<UpdaterRunResult>((resolve) => {
-      const proc = spawn(executable, args, { stdio: ['ignore', 'pipe', 'pipe'] })
+      const proc: ChildProcess = spawn(program, args, spawnOptions)
       const chunks: Buffer[] = []
 
-      proc.stdout.on('data', chunk => chunks.push(Buffer.from(chunk)))
-      proc.stderr.on('data', chunk => chunks.push(Buffer.from(chunk)))
-      proc.on('error', error => resolve({ success: false, output: error.message }))
-      proc.on('close', code => resolve({
+      proc.stdout?.on('data', (chunk: Buffer) => chunks.push(Buffer.from(chunk)))
+      proc.stderr?.on('data', (chunk: Buffer) => chunks.push(Buffer.from(chunk)))
+      proc.on('error', (error: Error) => resolve({ success: false, output: error.message }))
+      proc.on('close', (code: number | null) => resolve({
         success: code === 0,
         output: Buffer.concat(chunks).toString('utf-8')
       }))

cli/test/helpers/run-cli.ts

@@ -1,6 +1,9 @@
 export async function runCli(args: string[], env: Record<string, string> = {}) {
+  // Use Bun.which() to find bun in PATH, fallback to current executable
+  const bunPath = await Bun.which('bun') || process.execPath
+
   const proc = Bun.spawn({
-    cmd: ['bun', 'src/index.ts', ...args],
+    cmd: [bunPath, 'src/index.ts', ...args],
     cwd: new URL('../../', import.meta.url).pathname,
     env: { ...process.env, ...env },
     stdout: 'pipe',

cli/test/unit/stores/credentials-store.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, test } from 'bun:test'
+import { normalize } from 'path'
 import { createTempHome } from '../../helpers/temp-env'
 import { CredentialsStore } from '../../../src/stores/credentials-store'
 
@@ -8,7 +9,7 @@ describe('CredentialsStore', () => {
     const store = new CredentialsStore(env.home)
     await store.setToken('https://registry.example.com', 'sk_test')
     expect(await store.getToken('https://registry.example.com')).toBe('sk_test')
-    expect(store.path).toBe(`${env.home}/.skillhub/credentials.json`)
+    expect(normalize(store.path)).toBe(normalize(`${env.home}/.skillhub/credentials.json`))
     expect(await Bun.file(`${env.cwd}/credentials.json`).exists()).toBe(false)
   })
 })