Fix CI: update Go version to 1.25, use specific package paths

- .github/workflows/ci.yml: go-version '1.23' -> '1.25' to match go.mod
- All go build/vet/test/lint: use ./cmd/... ./internal/... instead of ./...
  to avoid picking up Go packages in node_modules/ (flatted)
- Makefile: same fix for test target

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
 
       - uses: actions/setup-go@v5
         with:
-          go-version: '1.23'
+          go-version: '1.25'
           cache: true
 
       - uses: actions/setup-node@v4
@@ -32,18 +32,18 @@ jobs:
         run: go mod download
 
       - name: Build
-        run: go build ./...
+        run: go build ./cmd/... ./internal/...
 
       - name: Vet
-        run: go vet ./...
+        run: go vet ./cmd/... ./internal/...
 
       - name: Test
-        run: go test -race -coverprofile=coverage.out ./...
+        run: go test -race -coverprofile=coverage.out ./cmd/... ./internal/...
 
       - name: Lint
         run: |
           curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin
-          $(go env GOPATH)/bin/golangci-lint run ./...
+          $(go env GOPATH)/bin/golangci-lint run ./cmd/... ./internal/...
 
       - name: Upload coverage
         uses: actions/upload-artifact@v4