ci: publish stable Docker tags and rename MCP image

[jack-arturo]

Summary

• Add a stable Docker tag for the main AutoMem image on release tags.
• Rename the MCP Docker workflow and publish the canonical ghcr.io/verygoodplugins/mcp-automem image.
• Keep dual-publishing the legacy ghcr.io/verygoodplugins/automem/mcp-sse-server image path for compatibility.

Test plan

• ruby -e 'require "yaml"; ARGV.each { |f| YAML.load_file(f); puts "ok #{f}" }' .github/workflows/docker-build.yml .github/workflows/docker-build-mcp-automem.yml
• git diff --check
• Pre-commit hooks during commit: check yaml, trailing whitespace, end-of-file, large files, merge conflicts, secrets, conventional commit
• actionlint not run locally because it is not installed

[Copilot]

Pull request overview

Updates the GitHub Actions Docker publishing workflows to add a stable tag on release tags and to publish the MCP image under a new canonical GHCR name while keeping the legacy image path for compatibility.

Changes:

• Add a stable Docker tag for release-tag builds (refs/tags/v*) for the main image workflow.
• Rename the MCP workflow and change its canonical published image to ghcr.io/<owner>/mcp-automem.
• Dual-publish the MCP image to both the new canonical image name and the legacy ghcr.io/<owner>/<repo>/mcp-sse-server path.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
.github/workflows/docker-build.yml	Adds stable Docker tag when building from v* tags.
.github/workflows/docker-build-mcp-automem.yml	Renames MCP workflow and publishes both canonical and legacy image names; adds stable tag on release tags.

Comments suppressed due to low confidence (1)

.github/workflows/docker-build-mcp-automem.yml:68

• The workflow now publishes the same digest under two image names (canonical ${{ env.IMAGE_NAME }} and legacy ${{ github.repository }}/mcp-sse-server), but the build provenance attestation later in the job is only generated for ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}. If you want compatibility consumers of the legacy image path to retain provenance verification, add a second attestation step (or otherwise ensure attestations are created for both published image names).