ci: use go 1.25 and pin GOTOOLCHAIN=local to fix covdata failure

go.mod requires go 1.25.6 but the workflow was requesting go-version: '1.24'.
With GOTOOLCHAIN=auto (the default), the runner auto-downloaded Go 1.25.6
which lacked the covdata sub-tool, causing the test job to fail with
'go: no such tool covdata' for all cmd/* packages.

Changes:
- Bump go-version from '1.24' to '1.25' to match the go.mod directive
- Add a 'Pin toolchain' step that sets GOTOOLCHAIN=local, preventing
  any further auto-upgrade surprises regardless of future go.mod bumps

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: multica-agent <github@multica.ai>

.gitea/workflows/ci.yml

@@ -14,25 +14,28 @@ jobs:
 
       - uses: actions/setup-go@v5
         with:
-          go-version: '1.23'
+          go-version: '1.25'
           cache: true
 
+      - name: Pin toolchain
+        run: echo "GOTOOLCHAIN=local" >> $GITHUB_ENV
+
       - name: Vet
-        run: GOTOOLCHAIN=local go vet ./...
+        run: go vet ./...
 
       - name: Test
-        run: GOTOOLCHAIN=local go test -v -race -coverprofile=coverage.out ./...
+        run: go test -v -race -coverprofile=coverage.out ./...
 
       - name: Coverage report
-        run: GOTOOLCHAIN=local go tool cover -func=coverage.out
+        run: go tool cover -func=coverage.out
 
       - name: Check internal package coverage
         run: |
-          COVERAGE=$(GOTOOLCHAIN=local go tool cover -func=coverage.out | grep "^github.com/hits/ExploreDNS/internal" | awk '{print $3}' | sed 's/%//' | awk '{sum+=$1; count++} END {if(count>0) print sum/count; else print 0}')
+          COVERAGE=$(go tool cover -func=coverage.out | grep "^github.com/hits/ExploreDNS/internal" | awk '{print $3}' | sed 's/%//' | awk '{sum+=$1; count++} END {if(count>0) print sum/count; else print 0}')
           echo "Average internal package coverage: ${COVERAGE}%"
 
       - name: Build
-        run: GOTOOLCHAIN=local go build -v ./...
+        run: go build -v ./...
 
   docker:
     runs-on: ubuntu-latest

go.mod

@@ -1,6 +1,6 @@
 module github.com/hits/ExploreDNS
 
-go 1.24.0
+go 1.25.6
 
 require (
 	github.com/miekg/dns v1.1.72