fix: add test parallelism and increase Windows CI timeout

- Increase Windows test timeout from 20m to 30m
- Add -parallel=4 flag to allow concurrent test execution
- Add t.Parallel() to safe table-driven tests in validate_test.go,
  autoimport_test.go, and sync_test.go

This should prevent the Windows CI timeout caused by the cumulative
runtime of cmd/bd tests exceeding 20 minutes.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -71,7 +71,7 @@ jobs:
         run: go build -v ./cmd/bd
 
       - name: Test
-        run: go test -v -short -timeout=20m ./...
+        run: go test -v -short -timeout=30m -parallel=4 ./...
 
   lint:
     name: Lint