chore(main): release 2.4.0

[github-actions]

🤖 I have created a release beep boop

2.4.0 (2026-03-20)

Features

• add dual-write JSON file store alongside MongoDB (096f46a)
• add dual-write JSON file store alongside MongoDB (b00f6dd)
• add stats page with cached operational statistics (5e8731f)

Bug Fixes

• allow pleaseNotify when ping frequency check triggers (a31cf02)
• clean up orphaned resources and subscriptions (21464c4)
• clean up orphaned resources and subscriptions (d84d3d7)
• clean up stale and orphaned entries from subscriptions.json (ff3fa87)
• clean up subscription docs with empty pleaseNotify arrays (c272b96)
• normalize IPv4-mapped IPv6 addresses in subscription URLs (c37902f)
• remove ping of feeds with missing resource during cleanup (725daeb)
• use https scheme for http-post subscriptions on port 443 (c796df3)
• use whenLastUpdate instead of whenLastCheck for stats (e1ac16c)

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[github-actions]

🤖 Created releases:

• v2.4.0

🌻