[API] Implement Pagination on All List Endpoints

[fentz26]

Problem

List endpoints return all results:

• Memory issues with large datasets
• Slow response times
• No cursor-based navigation

Proposed Solution

Cursor-Based Pagination

type PaginationParams struct {
    Limit  int    // max 100, default 20
    Cursor string // opaque cursor
}

type PaginatedResponse[T any] struct {
    Items      []T    `json:"items"`
    NextCursor string `json:"next_cursor,omitempty"`
    HasMore    bool   `json:"has_more"`
    Total      int    `json:"total,omitempty"`
}

// Cursor encoding
func EncodeCursor(id string, timestamp time.Time) string {
    data := fmt.Sprintf("%s:%d", id, timestamp.UnixNano())
    return base64.StdEncoding.EncodeToString([]byte(data))
}

API Changes

GET /v1/tasks?limit=20&cursor=abc123

Response:
{
    "items": [...],
    "next_cursor": "def456",
    "has_more": true,
    "total": 150
}

Acceptance Criteria

• All list endpoints support pagination
• Default limit: 20, max: 100
• Cursor-based (not offset-based)
• Link headers for navigation
• Backward compatibility (no cursor = first page)

References

• Evaluation Report Section: 1.1 API Design Quality