- Add "Built-in MCP" section to editor tools panel with OC Tools entry
- Rename "MCP Servers" to "External MCP" for clarity
- Replace broken SSE transport with WebStandardStreamableHTTPServerTransport
  (SSEServerTransport required Node.js ServerResponse, incompatible with Hono/Bun)
- Support SSE and streamable-http MCP servers in Claude engine (runtime.ts)

OC Tools connects agents to the existing oc-dev MCP server at /mcp,
giving any agent access to conclave management tools (list, create,
trigger, get runs, etc.) across all engines (Claude, OpenAI, Ollama).

Co-authored-by: OpenConclave <hello@openconclave.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>