Sync oci-enterprise-ai-chat to v0.9.9

[ralungei]

Summary

Brings the ai/gen-ai-agents/oci-enterprise-ai-chat/files/ asset up from v0.4.0 to v0.9.9, plus a README refresh documenting the new env vars. Supersedes the closed PR #2981, which only covered v0.5.0.

Highlights

• MCP static-client OAuth (oauth2-user). New auth type for providers without RFC 7591 dynamic client registration. One-click presets for Google, GitHub, Slack and Microsoft. User pre-creates the OAuth client in the provider's console, pastes credentials, the app runs PKCE.
• Client-side execution of delegated function_call MCP tools. Models like gpt-oss-120b emit MCP invocations as plain OpenAI-style function_call events that OCI does not run server-side. The client now executes the tool against the configured MCP server and chains a follow-up Responses request with function_call_output.
• MCP OAuth 2.1 cookie fix. Store only the refresh token (IDCS access JWT exceeds the 4KB cookie limit) and mint the access token on demand.
• NL2SQL via DBTools MCP with OAuth 2.1. New env var NEXT_PUBLIC_NL2SQL_MCP_URL points the in-chat Text-to-SQL flow at a hosted MCP server exposing generate_sql. System-prompt routing ensures the model passes the right semanticStoreId.
• file_search uniform across Gemini, Grok and gpt-oss-120b. Includes an explicit fallback when gpt-oss-120b cannot actually run it.
• Base path for OCI Generative AI Hosted Deployments. entrypoint.sh reads APPLICATION_BASE_URL (auto-injected by the platform) and falls back to BASE_PATH. New withBase() and useBaseRouter() helpers plus a global fetch patch (BasePathInit) keep existing root-absolute call sites working under a prefix.
• Stream handling. Stop fabricating PrematureStreamClose errors when OCI ends the SSE after a delegated function_call. Chips are only marked failed on real abort, network or stall errors.
• Style. Oracle Sans is now the global font baseline on body.
• Chore. Package rename to oci-enterprise-ai-chat, version 0.9.9, removed the SDD Generator add-on, model list trimmed to the client-safe set.
• Docs. README now documents NEXT_PUBLIC_NL2SQL_MCP_URL and APPLICATION_BASE_URL, and the Text-to-SQL feature is no longer flagged as "coming soon".

Files touched

34 files under ai/gen-ai-agents/oci-enterprise-ai-chat/: 33 source files plus the asset README. About +1,660 / -485.

Test plan

• npm run dev boots cleanly, no console errors
• OAuth oauth2.1 flow still works against MCP servers with dynamic registration
• OAuth oauth2-user flow with the Google preset: consent, token exchange, tool call returns data
• gpt-oss-120b: MCP tool runs client-side, model receives the output and finishes
• file_search works on Gemini and Grok, gracefully disabled on gpt-oss-120b
• OCI Hosted Deployment: app served under the applications/.../actions/invoke/ prefix, navigation and API calls all reach the right path
• Secret scan on the diff (OCIDs, IPs, IDCS domains, passwords, wallets) came back clean