Fix integration test compilation errors in cmd/bd

The integration tests were failing to compile due to several issues
introduced by API changes that weren't reflected in the test files:

1. daemon_test.go:
   - getPIDFilePath() signature changed: removed boolean parameter
   - getLogFilePath() signature changed: removed boolean parameter
   - Removed duplicate windowsOS constant (already in test_helpers_test.go)

2. daemon_parent_test.go:
   - Removed duplicate runGitCmd() function (already in git_sync_test.go
     with more functionality including date env vars)
   - Removed unused os/exec import

These fixes allow `go test -tags integration ./cmd/bd` to compile
successfully. The test suite can now be run to verify daemon and
sync branch functionality.

No behavioral changes - only fixing test compilation issues.

cmd/bd/daemon_parent_test.go

@@ -4,7 +4,6 @@
 package main
 
 import (
-	"os/exec"
 	"path/filepath"
 	"testing"
 )
@@ -39,10 +38,4 @@ func mustAbs(t *testing.T, path string) string {
 	return abs
 }
 
-func runGitCmd(t *testing.T, dir string, args ...string) {
-	cmd := exec.Command("git", args...)
-	cmd.Dir = dir
-	if err := cmd.Run(); err != nil {
-		t.Fatalf("git %v failed: %v", args, err)
-	}
-}
+// runGitCmd is defined in git_sync_test.go