fix: SABnzbd queue.speed format for Homepage rate widget

[scottcowan]

Summary

Format queue.speed like real SABnzbd ("1.3 M", "0 ", …) instead of formatBytes(...) + "/s" ("1.2 MB/s"), so clients that parse the short form (notably Homepage’s SABnzbd widget) show a non-zero rate when downloading.

How we know this is correct

1. SABnzbd contract — Official API docs show JSON such as "speed": "1.3 M" next to "kbpersec": "1296.02". That defines the intended string shape for queue.speed.
   https://sabnzbd.org/wiki/configuration/5.0/api

2. Homepage parser — fromUnits() splits queue.speed on a space and treats the second token as a single letter in B|K|M|G|T|P. Any other token (e.g. MB/s) makes indexOf fail and the rate becomes 0.
   https://github.com/gethomepage/homepage/blob/dev/src/widgets/sabnzbd/component.jsx

3. Homepage tests (behaviour spec) — Their widget test passes speed: "1.0 M" and asserts the derived rate; that codifies the same contract as SABnzbd’s examples.
   https://github.com/gethomepage/homepage/blob/dev/src/widgets/sabnzbd/component.test.jsx

4. Before / after — iPlayarr used formatBytes(totalSpeedKbs * 1024) + "/s" → strings like "500.00 KB/s", which do not match that parser. formatSabnzbdSpeedKbps() emits the short tier form so fromUnits matches SABnzbd + Homepage.

5. Tests — Unit tests for formatSabnzbdSpeedKbps (including 1296.02 → "1.3 M") and updated QueueEndpoint expectations; full npm test (373 tests) passes.

Related

• Homepage widget docs: https://gethomepage.dev/widgets/services/sabnzbd/
• Earlier queue-field work (crash fix, not rate): PR fix: add missing speed/size/sizeleft/kbpersec fields to SABnzbd queue response #225 / issue [BUG] SABnzbd queue API response missing speed/size fields — breaks Homepage widget #224.

[scottcowan]

The trailing space is intentional — it matches real SABnzbd's API output ("speed": "0 " when idle). The SABnzbd queue response shows this format ("speed": "1.3 M"), and Homepage's fromUnits() splits on the space to extract the unit letter, so trimming to "0" would mean no space is found, the split returns a single token, and the rate breaks.

I've added a test (fd62096) that documents this contract explicitly: '0 '.split(' ') gives ['0', ''] — unit is an empty string, not undefined, which is what proves the space was found.