Replace GitHub Actions cron

Crontap sends a repository dispatch request. GitHub still runs the workflow.

Prerequisites

Before using the required tools, check whether they are available. If any are missing, stop and offer the user exactly two choices:

1. Connect Crontap MCP at https://mcp.crontap.com/mcp. MCP access works on every Crontap tier.
2. Configure $CRONTAP_CLIENT_ID and $CRONTAP_API_KEY for the raw API. Raw API access requires Ultra.

Do not silently choose a path or continue until the user selects one.