Add a page schedule with rotation, Home Assistant trigger rules and a Stopwatch tab

- Schedule: daily blocks from a start time, each with up to 6 rotating pages
  or bitmaps (own duration), switching with the effect or instantly. A manual
  pick (Show tab, HA Mode) lasts until the next block; Back to schedule ends it.
- Rules: an HA state (=, is not, above, below) shows a page while true, adds it
  to the rotation while true, or shows it for N seconds when it becomes true.
  Each rule is polled at its own interval, with a 60 s back-off on errors.
- PageSelector (pure logic, tested) decides the shown page; schedule stored in
  NVS; HA sensor Shown page and button Back to schedule.
- Web UI: Schedule and Stopwatch tabs, bitmaps used by pages or rules in their
  own subsection, schedule in export/import. Version 2.6.0.

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

src/esp32/app.h

@@ -9,6 +9,7 @@
 #include "logic/display_controller.h"
 #include "logic/local_time.h"
 #include "logic/page.h"
+#include "logic/page_schedule.h"
 #include "logic/settings.h"
 #include "nano_link/nano_link.h"
 
@@ -25,8 +26,21 @@ void appLoadSettings();
 // restart_needed when the change only works after a restart (Home Assistant MQTT).
 const char *appSaveSettings(const Settings &settings, bool &restart_needed);
 
-// The page shown during the day: a dynamic page or a bitmap (stored in the settings)
+// The chosen page (settings): a dynamic page or a bitmap. With a schedule it is shown until
+// the next block starts (a manual pick), without one all the time.
 const char *appSelectPage(const char *name);
+
+// The schedule and trigger rules (validated, stored, used right away)
+const char *appSaveSchedule(const PageSchedule &schedule);
+const PageSchedule &appSchedule();
+// Ends a manual pick: the schedule decides again
+void appBackToSchedule();
+// The page or bitmap shown now, and why (e.g. "schedule", "chosen, until 17:00")
+const char *appShownPage();
+void appShowStatus(char *out, size_t size);
+// Decides the shown page (rules, schedule, chosen page); call every loop() before the
+// display controller
+void appPageLoop(bool time_valid, const LocalTime &time);
 // Left on the dots when the display switches off: OFF_PAGE_BLANK or a bitmap name
 const char *appSelectOffPage(const char *name);