Add setting to pass custom flags to marimo server (enable --mcp)

[ovidiususan]

Use Case
I use the VSCode extension to render notebooks because I need file links in markdown cells to open in VSCode (which doesn't work in browser). I also use Claude Code and need it to query notebook state via MCP.
Currently this is impossible because:

The extension spawns marimo without --mcp flag
There's no setting to add custom server arguments
MCP is not available via marimo.toml config

Proposed Solution
Add a setting like:
json{
"marimo.serverArgs": ["--mcp", "--no-token"]
}
Or more specifically:
json{
"marimo.enableMcp": true
}
Why This Matters
Marimo's integration with Claude Code is a key differentiator. The VSCode extension + MCP would enable a powerful workflow: notebooks rendered in VSCode with full AI agent integration. Currently users must choose between VSCode integration OR MCP, not both.

[manzt]

Thanks for the detailed use case! The challenge is that marimo-lsp doesn't run the CLI - it manages kernels directly via IPC, so there's no place to pass --mcp.

We probably need to rethink the integration to compose with VS Code's MCP ecosystem. VS Code 1.102+ has APIs for extensions to contribute MCP servers natively (registerMcpServerDefinitionProvider). We could explore having marimo-lsp register an MCP server that exposes notebook context directly.