Enhancement: Add input validation for API client methods

[rbansal42]

Overview

API client methods don't validate that required parameters are non-empty before making API calls. This leads to confusing API errors instead of clear validation messages.

Affected Methods

Workspaces API (internal/api/workspaces.go)

• GetWorkspace(ctx, workspaceSlug) - workspaceSlug could be empty
• ListWorkspaceMembers(ctx, workspaceSlug, opts) - workspaceSlug could be empty

Projects API (internal/api/projects.go)

• ListProjects(ctx, workspaceSlug, opts)
• GetProject(ctx, workspaceSlug, projectKey)
• CreateProject(ctx, workspaceSlug, opts)
• UpdateProject(ctx, workspaceSlug, projectKey, opts)
• DeleteProject(ctx, workspaceSlug, projectKey)

Branches API (internal/api/branches.go)

• ListBranches(ctx, workspace, repoSlug, opts)
• GetBranch(ctx, workspace, repoSlug, branchName)
• CreateBranch(ctx, workspace, repoSlug, opts)
• DeleteBranch(ctx, workspace, repoSlug, branchName)

Also in existing code (internal/api/repositories.go)

• Same pattern exists in repository methods

Proposed Solution

Add validation at the start of each method:

func (c *Client) GetProject(ctx context.Context, workspaceSlug, projectKey string) (*ProjectFull, error) {
    if workspaceSlug == "" {
        return nil, fmt.Errorf("workspaceSlug is required")
    }
    if projectKey == "" {
        return nil, fmt.Errorf("projectKey is required")
    }
    // ... rest of method
}

Benefits

• Clear error messages for invalid input
• Fail fast before making network request
• Easier debugging

Acceptance Criteria

• Add validation for all API methods with required parameters
• Add test cases for validation errors
• Consistent error message format