Add container label & improve registry script

[MattBabbage]

This pull request updates the release workflow and configuration to improve version management, automate validation, and align metadata with MCP requirements. The most important changes are grouped below.

All PRs will be squashed into one, lots of trial and error took place.

[Copilot]

Pull Request Overview

This pull request updates the release workflow and configuration to improve version management, automate validation, and align metadata with MCP requirements.

• Adds MCP server label to Docker container and uses dynamic versioning
• Improves the registry release workflow with Go setup, tag fetching, and validation
• Removes hardcoded version strings and unused remote configuration

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
server.json	Updates version placeholders and package identifier, removes unused remotes section
Dockerfile	Adds MCP server annotation label for proper identification
.github/workflows/registry-releaser.yml	Enhances workflow with Go setup, improved publisher installation, and configuration validation

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