v1.14.2

v1.14.2 — MAC-based device dedup + remove button on offline cards

Two related fixes for the "scanned a device at DHCP IP, set a static
IP, ended up with duplicate cards" workflow:

1. /api/devices/add now compares the new device's macAddr against the
   last-known macAddr of every existing tracked device. Same MAC at a
   different IP transparently re-binds: the old entry is removed, the
   existing label is carried over to the new IP, the rebound_from field
   in the response tells the caller what happened. Without this you'd
   end up with two cards for one Bitaxe, one perpetually offline.

2. Offline compact cards now show a × button (top-right) that calls
   /api/devices/remove after a confirm() prompt. Click handler stops
   propagation before the wrapping <a> can fire. Online cards still
   route through the device-detail Remove button.

APP_VERSION bump 1.14.1 → 1.14.2, matching footer bumps.