fix(ci): bump golangci-lint to v2.4 + migrate buildkit-cache-dance to cache-map (#34)

* chore(ci): bump golangci-lint-action version to v2.4

Pin v2.1 (binary built with Go 1.24) refused to load configs targeting
Go 1.25.0, blocking dependabot PRs #28 and #29 which bump go.mod's go
directive. v2.4 is built with Go 1.25 and lints both 1.24 and 1.25
targets.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix(ci): migrate buildkit-cache-dance v3 inputs (cache-source → cache-map)

v3 deprecated cache-source and now requires explicit cache-map. Without
this, v3 falls back to auto-discovery defaults that try to mkdir
/var/cache/apk on the runner and fail with EACCES, breaking every
Docker Publish run on main since #21 landed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ysyneu

.github/workflows/docker-publish.yml

@@ -30,6 +30,7 @@ jobs:
           cosign-release: "v2.2.4"
 
       - name: Set up Docker Buildx
+        id: setup-buildx
         uses: docker/setup-buildx-action@v4
 
       - name: Log into registry ${{ env.REGISTRY }}
@@ -56,6 +57,7 @@ jobs:
             type=raw,value=latest,enable=${{ github.ref_type == 'tag' && startsWith(github.ref, 'refs/tags/v') && !contains(github.ref, '-') }}
 
       - name: Go Build Cache for Docker
+        id: cache
         uses: actions/cache@v5
         with:
           path: go-build-cache
@@ -64,7 +66,12 @@ jobs:
       - name: Inject go-build-cache
         uses: reproducible-containers/buildkit-cache-dance@1b8ab18fbda5ad3646e3fcc9ed9dd41ce2f297b4 # v3.3.2
         with:
-          cache-source: go-build-cache
+          builder: ${{ steps.setup-buildx.outputs.name }}
+          cache-map: |
+            {
+              "go-build-cache": "/root/.cache/go-build"
+            }
+          skip-extraction: ${{ steps.cache.outputs.cache-hit }}
 
       - name: Build and push Docker image
         id: build-and-push

.github/workflows/lint.yml

@@ -23,4 +23,4 @@ jobs:
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v9
         with:
-          version: v2.1
+          version: v2.4