Add dynamic pages with clock, date, Home Assistant values and fonts

The hardcoded clock is now the built-in dynamic page "Clock". A dynamic page
has a background bitmap per time of day and up to 8 elements (clock, date,
Home Assistant value, text), each with position, alignment, font and overlay.
Pages are drawn on the ESP32, also for the web previews.

- Pages tab in the web UI: page editor with drag and drop, font upload
  (TTF/OTF converted in the browser to the FDF1 dot font format)
- Built-in fonts Small, Normal, Large and Full height (generated by
  tools/make_builtin_fonts.py), built-in bitmaps Pikachu and Pikachu yawning
- Home Assistant values over the REST API (URL and token in the HA tab)
- Settings version 4: evening settings removed (now time slots of the Clock
  page), old records are converted
- HA Mode dropdown lists the dynamic pages and bitmaps

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

CLAUDE.md

@@ -138,6 +138,16 @@ See README.md for the overview.
 - Bitmaps on LittleFS in the `spiffs` partition (`/bitmaps/<name>.bin`, 209 bytes). Names
   are restricted (`validBitmapName`), which also makes them safe in paths and JSON.
 - The display mirror comes from the driver's shadow buffer (`BROSE9323::shownPixel`).
+- Dynamic pages (`logic/page.h`): background per time slot + elements, stored as a
+  versioned binary struct (`display/page_store.cpp`, bump `VERSION` when `DynamicPage`
+  changes). They are drawn only on the ESP32 (`logic/page_render`), also for the web
+  previews, so there is one renderer. Pages and bitmaps share one namespace (checked in
+  `app.cpp`); things a page uses can't be deleted. The built-in page "Clock" replaces the
+  old hardcoded clock (also the default and the HA "Clock" option).
+- Fonts use the "FDF1" format of `logic/font.h`; the web page writes the same format.
+  `logic/builtin_fonts.cpp` is generated: change `tools/make_builtin_fonts.py` and rerun it.
+- Home Assistant values come from HA's REST API (`net/ha_api`), one blocking request per
+  `loop()` with `HA_HTTP_TIMEOUT`. Keep it that way (watchdog, OTA).
 - Check the page's JavaScript after changes: extract the `<script>` part and run
   `node --check` on it (node is installed).