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>

dependencies.lock

@@ -0,0 +1,20 @@
+dependencies:
+  espressif/mdns:
+    component_hash: b679eafd0acae2066e2645bd91d073e33ca5be515e2545cd3c4e55a3e3bce3cb
+    dependencies:
+    - name: idf
+      require: private
+      version: '>=5.0'
+    source:
+      registry_url: https://components.espressif.com/
+      type: service
+    version: 1.13.1
+  idf:
+    source:
+      type: idf
+    version: 5.5.5
+direct_dependencies:
+- espressif/mdns
+manifest_hash: e5eba11c864076c14a58153c7f761bec2b064244e66ca3f76c0dc170db907329
+target: esp32p4
+version: 2.0.0