UI_ShowClockPage()/UI_ShowSetTimePage() now take weekday/day/month(/year)
and build the date bar dynamically via Build_DateString() instead of
the fixed placeholder string. app_home.c reads the full date from RTC
via PCF8563_ReadDateTime() and recalculates weekday since the RTC's
stored date may differ from the software clock's. config.h exposes
current_day/month/year/weekday alongside the existing time fields so
main.c's debug commands don't need a separate include.
Adds KEY_EVENT_SECOND_TICK, generated once per real second from
Clock_IncMS() via a new second_tick_flag and pushed through the normal
event queue, so every foreground App's onEvent() receives it and
decides independently whether to act. Removes the old global
inactivity_timer (60s sleep from anywhere) entirely. HomeApp now
accumulates its own idle-second counter and sleeps after 10s idle
specifically while on the home screen; MenuApp's existing 10s
auto-close is converted from onRun() polling to the same tick+reset
pattern for consistency. Any non-tick key event resets each app's own
counter to 0.
Splits the ad-hoc menu_level state machine into standalone Apps with a
uniform parent/child exit convention (long-press CONFIRM -> parent):
clock_app renamed to home_app (boot-default), new set_clock_app
extracted from home_app's time-edit mode, new ipc_bind_app extracted
from menu_app's old level-2 screen, and the sensor-type selection step
merged into pair_app as its new initial state. menu_app now only holds
the 4-item top-level list (language toggle inline). Also makes both
menu_app and pair_app's up/down navigation cyclic (wraps at both ends).
