- Add POST /api/homekit/pair endpoint that calls hap.Pair() from go2rtc
- Rewrite homekit.html with PIN input UI (XXX-XX-XXX format)
- Auto-advance between digit fields, paste support, error/success states
- On successful pairing, redirect to create.html with homekit:// URL
- Pass mdns_port and mdns_paired from probe to homekit.html
- Detect HomeKit cameras regardless of pairing status