chore: split result data JSON blob into dedicated columns

[svenvg93]

📃 Description

Replaces the generic data JSON blob on the results table with dedicated, typed columns for each Ookla metric. This makes individual fields queryable and indexable without having to dig into JSON, and aligns the database schema with the OoklaResult DTO introduced alongside it.

Existing rows are backfilled from their stored JSON during the migration.

🪵 Changelog

➕ Added

• OoklaResult DTO (app/Data/OoklaResult.php) to map Ookla JSON payloads to typed properties and back to model attributes
• Dedicated columns on the results table for ping (ping_jitter, ping_low, ping_high), download (download_jitter, download_latency_iqm, download_latency_low, download_latency_high, download_elapsed), upload (upload_jitter, upload_latency_iqm, upload_latency_low, upload_latency_high, upload_elapsed), packet_loss, isp, ip_address, server info (server_id, server_name, server_host, server_ip, server_country, server_location), result_url, and error_message
• Add DB indexes for created_at, status, download, upload, ping, scheduled, healthy, server_id, server_name, ip_address, dispatched_by
  • Closes [Bug]: SQLite missing indexes on results table cause HTTP 504 timeouts on /admin/results with large datasets #2803