Adds espressif/mqtt and mdns as the project's first external managed
component dependencies (neither ships with ESP-IDF core in v6.0.2
anymore). Once Wi-Fi connects, the device advertises itself on the LAN
as kvida-xxxxxx.local and serves a persistent settings page there for
MQTT broker host/port and credentials -- the ongoing config channel
beyond the one-time Wi-Fi captive portal.
mDNS auto-discovery of _mqtt._tcp was the original plan, but verified
against a real Home Assistant OS + Mosquitto add-on that it doesn't
reliably answer PTR queries on the LAN (confirmed with a raw mDNS
query from the host, parsed properly with dnspython after an earlier
naive byte-check gave a false positive). Manual host/port entry is
now the primary path; mDNS discovery still runs as a secondary
fallback attempt, retried every 30s, in case it works on other
networks.
On MQTT_EVENT_CONNECTED, publishes retained HA MQTT Discovery for a
diagnostic "connectivity" binary_sensor (grouped under a Kvida/Xylon
device block) plus an online/offline availability topic driven by
MQTT's own LWT. Verified end-to-end on real hardware: the device
appears in Home Assistant with a "Connected" Connectivity sensor.
Also extracts url_decode() (previously local to commissioning.cpp)
and a new device_id() helper into shared headers, since both
commissioning's Wi-Fi form and the new MQTT settings form need them.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Implements first-boot Wi-Fi setup with no companion app required: a
SoftAP + captive portal (DNS wildcard redirect, DHCP option 114, HTTP
form) lets the user submit Wi-Fi credentials from any browser. On
submit, credentials are saved to NVS and the device switches to STA
mode; on subsequent boots it reconnects automatically via stored
credentials. dns_server.c/.h are vendored from ESP-IDF's official
captive_portal example (Unlicense/CC0).
Requests both link-local and global IPv6 addresses once the STA
connection has an IPv4 address (not on WIFI_EVENT_STA_CONNECTED --
esp_netif_create_ip6_linklocal() reliably fails there because
esp-netif's own handler, which marks the lwIP netif "up", hasn't run
yet due to event-handler registration order). Verified end-to-end on
real ESP32-C6 hardware: SoftAP comes up, credential submission works,
STA reconnects on reboot, and both a link-local and a router-assigned
global IPv6 address are obtained via SLAAC.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
