Add support for SUPABASE_ACCESS_TOKEN environment variable

[toyamarinyon]

• Allow access token to be set via environment variable (SUPABASE_ACCESS_TOKEN) as an alternative to the CLI flag
• Improves developer experience by allowing tokens to be stored in environment instead of passed on command line

[gregnr]

Great addition, thanks @toyamarinyon 🎉

I added some docs to the README so that everyone is aware of this.

[scheung38]

Hi @gregnr

Is this correct?

  "supabase": {
      "command": "npx",
      "args": [
        "-y",
        "@supabase/mcp-server-supabase@latest",
        "$SUPABASE_ACCESS_TOKEN"
      ]
    }
  }
}

ps aux | grep npx does not seem to pick it up even after source .env

.env
SUPABASE_ACCESS_TOKEN="sbp_<MY_TOKEN>"