Add direct client methods for project/board operations:
- GetAllProjects(ctx) - list all accessible projects
- GetProjectByID(ctx, projectID) - get project by ID
- GetProjectByName(ctx, name) - get project by name
All methods:
- Use context for cancellation support
- Return ErrProjectNotFound when project doesn't exist
- Properly wrap errors with context
Closes: kanboard-api-apl
