Build images with buildx action instead of goreleaser

[creativeprojects]

No description provided.

[Copilot]

Pull request overview

This PR updates the project’s container image build pipeline to use Docker Buildx (via GitHub Actions and Makefile targets) rather than relying on GoReleaser-driven image publishing, and adjusts the Dockerfile to be multi-arch aware.

Changes:

• Add Makefile targets to download per-arch restic/rclone binaries and build a multi-arch Docker image with docker buildx.
• Update build/Dockerfile to use BuildKit’s TARGETARCH for selecting the correct binaries during multi-arch builds.
• Update CI workflows: snapshot publishing now uses docker/build-push-action, and several OS test workflows adjust path ignore rules.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 19 comments.

Show a summary per file

File	Description
Makefile	Adds docker-image / docker-builder targets to build a multi-arch image with buildx.
build/Dockerfile	Switches from ARCH to TARGETARCH to support buildx multi-platform builds.
.github/workflows/snapshot.yml	Replaces GoReleaser + manual manifest logic with buildx build-and-push action.
.github/workflows/ubuntu.yml	Adjusts workflow path-ignore filters (intended to reduce workflow churn).
.github/workflows/windows.yml	Adjusts workflow path-ignore filters (intended to reduce workflow churn).
.github/workflows/ssh.yml	Adjusts workflow path-ignore filters (intended to reduce workflow churn).
.github/workflows/openbsd.yml	Adjusts workflow path-ignore filters (intended to reduce workflow churn).
.github/workflows/netbsd.yml	Adjusts workflow path-ignore filters (intended to reduce workflow churn).
.github/workflows/macos.yml	Adjusts workflow path-ignore filters (intended to reduce workflow churn).
.github/workflows/freebsd.yml	Adjusts workflow path-ignore filters (intended to reduce workflow churn).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.76%. Comparing base (ef12616) to head (9e80a85).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #664   +/-   ##
=======================================
  Coverage   81.76%   81.76%           
=======================================
  Files         161      161           
  Lines       12009    12009           
=======================================
  Hits         9818     9818           
  Misses       1692     1692           
  Partials      499      499           

Flag	Coverage Δ
unittests	80.01% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.