0.6.0

[0.6.0] - 2026-08-05

Added

• MqttProfile — stored MQTT broker settings (enabled, host, port, TLS,
  username, password) with checkConfig(), saveCfg()/loadCfg() and
  toJson(). It lives here rather than in a library of its own for the same
  reason the NTP servers do: it is something a networked device stores in order
  to reach a service, and the two are always deployed together. It knows nothing
  about MQTT itself — no client, no topics, no connection — so the same profile
  serves an ESP32 task, an ESP8266 loop and an AVR without a portal.
  Topics are deliberately absent, being project-specific; the virtual hooks are
  there for a subclass that needs them.
• enabled is a field of its own rather than an empty host standing in for it:
  "switched off" and "not configured yet" are different facts, and a device taken
  off the broker for a while should not have to forget its address to do it.
• MqttProfile locks the same way NetworkProfile does — a std::timed_mutex
  where preemption exists (ESP32), a no-op on AVR and ESP8266 — because the
  settings are copied field by field: the portal saving while a client task
  reads would otherwise hand out half of each. getConfig() and setConfig()
  return bool accordingly. checkConfig() takes the config as a parameter, as
  NetworkProfile's does, so validation runs on a staged copy and needs no lock
  at all — but it is virtual rather than static, since a static one called
  through a base reference silently skips a subclass's own rules.
• detail/prefs_tools.h with prefs_putStr() — the empty-string storage rule
  (store non-empty, remove the key otherwise) now has one implementation instead
  of one per profile class.

Changed

• Passing a subclass's config to a base-class checkConfig(), isValidConfig()
  or setConfig() is now a compile error rather than a silent half-check. These
  are static, so the compiler picks by declared type: a WiFiConfig handed to
  the base version — which is what happens the moment a caller holds a
  NetworkProfile& — checked the addressing, skipped the SSID, password and
  TX-power rules, and reported Ok. Deleted derived-type overloads now catch it.

  Where it fires, either call through the concrete type
  (WiFiProfile::checkConfig(cfg)), which is nearly always what was meant, or
  state that only the addressing is of interest:
  checkConfig(static_cast<const NetworkConfig&>(cfg)). Slicing a config into a
  NetworkConfig variable first still loses the subclass fields — by then they
  are gone, and no signature can catch that. MqttProfile carries the same
  guard.

  Impact on the dependent libraries was one call site, inside WiFiProfile
  itself; NetworkManager, AsyncConfigPortal and AsyncWiFiPortal all already
  called through the concrete type or cast explicitly.

Note

• The MQTT password is not written to toJson(), matching WiFiProfile: a
  backup file may travels through mail and cloud storage. Restoring one
  therefore needs the broker password entered again.