Function sanitiseMermaidId

sanitiseMermaidId(id: string): string
Sanitise an identifier for use in Mermaid diagrams by replacing non-alphanumeric/underscore characters with an underscore.
Parameters
- id: string
  Identifier to sanitise
Returns string
Example
```
// sanitiseMermaidId('I1:Name') // 'I1_Name'
```
- Defined in operations/graph-shared.ts:14