Step 2a (1/2): mDNS hostname.local and _http._tcp

- aes67_net: espressif/mdns 1.13.1 (managed component, pinned in
  dependencies.lock). Advertises <net.hostname>.local and the web UI as
  _http._tcp port 80. net apply callback renames live.
- First config value actually applied: net.hostname.
- Docs: mDNS in the core Network section; build order gets step 2a
  (mDNS, then LLDP).
- Verified on board: p4-aes67.local resolves via raw mDNS and getent,
  http://p4-aes67.local/ answers, service shows in _http._tcp browse;
  live rename to p4-rename and back works (after ~1 s probing).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -37,6 +37,7 @@ Repo: https://gitea.apointless.space/bsncubed/aes67-ESP32-P4
 - [x] 0. Check chip revision and flash size; create IDF project and empty component stubs (layout in aes67-core-base.md). Set up the OTA partition table (two app slots, no factory) and PROJECT_VER from git now, so the layout never changes later.
 - [x] 1. Ethernet: IP101 up, DHCP, IP logged. Ping works.
 - [x] 2. Web server + config store (cJSON in NVS) + embedded index.html; /api/config, /api/status (stub values), /api/reboot.
+- [ ] 2a. Finding the device: mDNS (hostname.local + _http._tcp), then LLDP (switch shows name + IP).
 - [ ] 2b. Firmware update: /api/ota upload + rollback self-test. Test: update to a new build, then deliberately flash a build that fails its self-test and confirm it rolls back. After this, flash over the network; keep USB for recovery.
 - [ ] 3. PTP TimeReceiver: lock to an existing GM (Riedel), fill `status.ptp`. Confirm EMAC hardware timestamps work. First check whether the installed ESP-IDF has a PTP example/component for the P4 before writing one.
 - [ ] 4. AES67 TX with a 1 kHz test tone, PTP-paced; /stream.sdp. Verify: import SDP on a Riedel Artist 4-wire AES67 port, and check packets/timestamps in Wireshark.