Add cursor-based pagination to route generation

[PAMulligan]

Description

The pipeline currently generates offset-based pagination. Add cursor-based pagination as an option, which is better suited for real-time data, infinite scroll, and large datasets.

Why

Offset pagination has well-known issues with large datasets (performance degrades as offset increases) and consistency issues (items shift between pages as new data is inserted). Cursor-based pagination solves both. The `pipeline.config.json` already has `cursorPaginationAvailable: true` but no implementation exists.

Current State

`pipeline.config.json`:
```json
"pagination": {
"defaultLimit": 20,
"maxLimit": 100,
"strategy": "offset",
"cursorPaginationAvailable": true
}
```

Acceptance Criteria

• Implement cursor-based pagination in the `route-generation` skill
• Support both opaque cursors (base64-encoded) and keyset pagination
• Generate cursor pagination response format:
  ```json
  {
  "data": [...],
  "meta": {
  "hasNextPage": true,
  "hasPreviousPage": false,
  "startCursor": "abc123",
  "endCursor": "xyz789"
  }
  }
  ```
• Allow per-endpoint selection of pagination strategy in `build-spec.json`
• Add Zod schemas for cursor pagination query params (`?cursor=abc&limit=20`)
• Generate integration tests for cursor pagination
• Update the `api-documentation` skill to document cursor endpoints
• CI passes

[github-actions]

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