fix(provider): include providerID in SDK cache key (#11020)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

packages/opencode/src/provider/provider.ts

@@ -977,7 +977,7 @@ export namespace Provider {
           ...model.headers,
         }
 
-      const key = Bun.hash.xxHash32(JSON.stringify({ npm: model.api.npm, options }))
+      const key = Bun.hash.xxHash32(JSON.stringify({ providerID: model.providerID, npm: model.api.npm, options }))
       const existing = s.sdk.get(key)
       if (existing) return existing