Implement Link API methods

- GetAllTaskLinks: retrieve all links for a task
- CreateTaskLink: create link between two tasks
- RemoveTaskLink: delete a task link
- TaskScope.GetLinks and LinkTo for fluent API
- Link types include "blocks", "is blocked by", etc.
- Comprehensive test coverage

links.go

@@ -0,0 +1,56 @@
+package kanboard
+
+import (
+	"context"
+	"fmt"
+)
+
+// GetAllTaskLinks returns all links for a task.
+func (c *Client) GetAllTaskLinks(ctx context.Context, taskID int) ([]TaskLink, error) {
+	params := map[string]int{"task_id": taskID}
+
+	var result []TaskLink
+	if err := c.call(ctx, "getAllTaskLinks", params, &result); err != nil {
+		return nil, fmt.Errorf("getAllTaskLinks: %w", err)
+	}
+
+	return result, nil
+}
+
+// CreateTaskLink creates a link between two tasks.
+// The linkID specifies the type of relationship (e.g., "blocks", "is blocked by").
+// Returns the ID of the created link.
+func (c *Client) CreateTaskLink(ctx context.Context, taskID, oppositeTaskID, linkID int) (int, error) {
+	params := map[string]int{
+		"task_id":          taskID,
+		"opposite_task_id": oppositeTaskID,
+		"link_id":          linkID,
+	}
+
+	var result int
+	if err := c.call(ctx, "createTaskLink", params, &result); err != nil {
+		return 0, fmt.Errorf("createTaskLink: %w", err)
+	}
+
+	if result == 0 {
+		return 0, fmt.Errorf("createTaskLink: failed to create link")
+	}
+
+	return result, nil
+}
+
+// RemoveTaskLink deletes a task link.
+func (c *Client) RemoveTaskLink(ctx context.Context, taskLinkID int) error {
+	params := map[string]int{"task_link_id": taskLinkID}
+
+	var success bool
+	if err := c.call(ctx, "removeTaskLink", params, &success); err != nil {
+		return fmt.Errorf("removeTaskLink: %w", err)
+	}
+
+	if !success {
+		return fmt.Errorf("removeTaskLink: delete failed")
+	}
+
+	return nil
+}