KV binding defaults to STORAGE when driver explicitly set

[onmax]

when working on #765, i found that when explicitly setting driver: 'cloudflare-kv-binding' in hub.kv config, the binding property is not set to default 'KV', causing unstorage to use 'STORAGE'.

Reproduce

// nuxt.config.ts
export default defineNuxtConfig({
  hub: {
    kv: {
      driver: 'cloudflare-kv-binding',
      namespaceId: '<id>'
    }
  }
})

Deploy to Cloudflare Workers → 500 error: [unstorage] [cloudflare] Invalid binding 'STORAGE': undefined

Cause

resolveKVConfig() in src/kv/setup.ts returns early when driver is explicitly set (line 16), skipping the Cloudflare defaults merge at lines 48-51 that adds binding: 'KV'.

Workaround

Add binding: 'KV' explicitly.

Expected

binding: 'KV' should be merged even when driver is explicitly specified.