move 'make check' into Dockerfile, simplify CI to just 'docker build .'

Per reviewer feedback: the Dockerfile now runs 'make check' early in
its build process (after dependencies are extracted). The CI workflow
is simplified to just run 'docker build .', which implicitly runs
'make check' as part of the Docker build.

.gitea/workflows/check.yml

@@ -8,17 +8,6 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
-      - uses: actions/setup-go@40f1582b2485089dde7abd97c1529aa768e1baff # v5
-        with:
-          go-version-file: go.mod
-      - name: Install golangci-lint
-        run: go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@5d1e709b7be35cb2025444e19de266b056b7b7ee # v2.10.1
-      - name: Install protoc-gen-go
-        run: go install google.golang.org/protobuf/cmd/protoc-gen-go@4dfe9d308b477d29e8c2b6d75abf3e78aafe3cb8 # v1.28.1
-      - name: Generate protobuf
-        run: |
-          sudo apt-get update && sudo apt-get install -y protobuf-compiler
-          cd mfer && go generate .
-      - name: Run checks
-        run: make check
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13894f8d5 # v4
+      - name: Build Docker image (runs make check internally)
+        run: docker build .

Dockerfile

@@ -17,6 +17,7 @@ ARG DRONE_COMMIT_SHA unknown
 RUN mkdir -p "$(go env GOMODCACHE)" && cd "$(go env GOMODCACHE)" && \
     zstdmt -d --stdout /build/modcache.tzst | tar xf - && \
     rm /build/modcache.tzst && cd /build
+RUN make check
 RUN \
     cd mfer && go generate . && cd .. && \
     GOPACKAGESDEBUG=true golangci-lint run ./... && \