Add Completion/Object Endpoints

[smashedr]

useCompletion: https://ai-sdk.dev/docs/reference/ai-sdk-ui/use-completion
useObject: https://ai-sdk.dev/docs/reference/ai-sdk-ui/use-object

---

• ✅ Add /completion and /object endpoint
• ✅ Add DISABLE_CLIENT_INSTRUCTIONS option
• ✅ Add PROVIDER_USER_AGENT option
• ✅ Change INSTRUCTIONS to INSTRUCTIONS_CHAT (backwards compatible)
• ✅ Change system to instructions (backwards compatible)
• ✅ Change / to /chat (backwards compatible)
• ✅ Update Dependencies and Workflows
• ⚠️ Change AI_SDK_LOG_WARNINGS logic to match SDK (see WARNING)

Warning

AI_SDK_LOG_WARNINGS has changed and is now 1:1 with the SDK.
Undefined or false will DISABLE and true will ENABLE.
Reference: https://ai-sdk.dev/docs/ai-sdk-ui/error-handling