fix: resolve golangci-lint errors (errcheck, gosec, unparam)

- orphans.go: check fmt.Scanln return value
- edit.go: #nosec G204 for trusted $EDITOR execution
- sync_git.go: #nosec G204 for git commands with internal branch names
- worktree_cmd.go: #nosec G304/G306 for .gitignore file operations
- migrations: handle rows.Close() error
- doctor_pollution.go: mark unused path parameter

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/edit.go

@@ -131,6 +131,7 @@ Examples:
 		_ = tmpFile.Close()
 
 		// Open the editor
+		// #nosec G204 -- editor comes from trusted $EDITOR/$VISUAL env or known defaults
 		editorCmd := exec.Command(editor, tmpPath)
 		editorCmd.Stdin = os.Stdin
 		editorCmd.Stdout = os.Stdout