[MCP] Automatically publish to MCP registry using goreleaser

[foxish]

Using https://goreleaser.com/customization/mcp/
The manifest I used to manually push it was:

{
  "$schema": "https://static.modelcontextprotocol.io/schemas/2025-12-11/server.schema.json",
  "name": "io.github.signadot/cli",
  "title": "Signadot MCP Server",
  "description": "Connect to Signadot to manage ephemeral environments and route traffic to local services.",
  "repository": {
    "url": "https://github.com/signadot/cli",
    "source": "github"
  },
  "version": "1.4.0",
  "packages": [
    {
      "registryType": "mcpb",
      "identifier": "https://github.com/signadot/cli/releases/download/v1.4.0/signadot-mcp_darwin_arm64.tar.gz",
      "fileSha256": "9f9a239c0304debd5ae1235861eed2679a0aea04435f7ba96f46783a4be0aece",
      "transport": {
        "type": "stdio",
        "command": "signadot",
        "args": ["mcp"]
      },
      "environmentVariables": [
        {
          "name": "SIGNADOT_API_KEY",
          "description": "Signadot API Key",
          "isRequired": true,
          "isSecret": true
        }
      ]
    },
    {
      "registryType": "mcpb",
      "identifier": "https://github.com/signadot/cli/releases/download/v1.4.0/signadot-mcp_darwin_amd64.tar.gz",
      "fileSha256": "3978acff3e6037161fd8801b346925db9ae3cbb17807a0913ef4cf01119ee119",
      "transport": {
        "type": "stdio",
        "command": "signadot",
        "args": ["mcp"]
      },
      "environmentVariables": [
        {
          "name": "SIGNADOT_API_KEY",
          "description": "Signadot API Key",
          "isRequired": true,
          "isSecret": true
        }
      ]
    },
    {
      "registryType": "mcpb",
      "identifier": "https://github.com/signadot/cli/releases/download/v1.4.0/signadot-mcp_linux_amd64.tar.gz",
      "fileSha256": "b81f034adb628a1a7f0abe2e79a452fea1d1e9d53786f3bc1bf5760ba0055546",
      "transport": {
        "type": "stdio",
        "command": "signadot",
        "args": ["mcp"]
      },
      "environmentVariables": [
        {
          "name": "SIGNADOT_API_KEY",
          "description": "Signadot API Key",
          "isRequired": true,
          "isSecret": true
        }
      ]
    },
    {
      "registryType": "mcpb",
      "identifier": "https://github.com/signadot/cli/releases/download/v1.4.0/signadot-mcp_linux_arm64.tar.gz",
      "fileSha256": "9a5aa540c1a1f8064b14861f1f5526cba19061e1d4d6e157ac6dbd92c048d3c9",
      "transport": {
        "type": "stdio",
        "command": "signadot",
        "args": ["mcp"]
      },
      "environmentVariables": [
        {
          "name": "SIGNADOT_API_KEY",
          "description": "Signadot API Key",
          "isRequired": true,
          "isSecret": true
        }
      ]
    }
  ]
}