[Feature]: Bonjour discovery — handle panels announced on multiple interfaces

[maxajbarlow]

Follow-up from

• Issue [Feature]: Add bonjour support #18 (Bonjour discovery)
• PR feat: add Bonjour discovery for panels (#18) #21, which adds the discovery picker but deliberately does not address this.

Context

Panels have three network interfaces (Media1, Config1, Media2). The avahi-browse output in #18 shows the _riedel._tcp service being announced per-interface, so a single physical panel may appear multiple times in Companion's discovered-device list — once per interface it advertises on, each with a different IP.

+   eth1 IPv4 Riedel-RSP-1216HL-FA-CA-DE-7   _riedel._tcp   local
   hostname = [Riedel-RSP-1216HL-FA-CA-DE.config1.local]
   address = [192.168.44.160]
   port = [80]
   txt = ["SerialNumber=1234567890123" "FirmwareVersion=2.0.0-82..." "DeviceType=RSP-1216HL" "DeviceName=Riedel-RSP-1216HL-FA-CA-DE" "ApiVersion=1.0.0"]

Open questions (need a physical RSP-1216HL to answer)

• Does the panel announce _riedel._tcp on all interfaces (Media1/Config1/Media2), or only the config interface?
• If multiple, do they share the same SerialNumber TXT field (so duplicates can be de-duplicated/grouped by serial in the UI)?
• Is the WebSocket control API reachable on every announced interface, or only some? (i.e. is picking the "wrong" interface's IP a problem?)
• Should the picker label disambiguate entries (e.g. include the interface name or IP) so a user can tell duplicate-looking entries apart?

Possible outcomes

Depending on the answers: leave as-is (acceptable to show one entry per interface), filter to a preferred interface, or de-duplicate by SerialNumber in the TXT record.

Environment to reproduce

Any RSP-1216HL with multiple interfaces configured, running firmware 2.0.0-82 or similar, with Companion's Bonjour discovery enabled after PR #21 merges.