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>

src/esp32/README.md

@@ -19,7 +19,12 @@ debug output. Wiring is described in the [main README](../../README.md#wiring-be
 | `logic/display_controller.*` | Decides what is shown and when the display is powered: page, live mode, schedule, Home Assistant switches (`DisplayController`) |
 | `logic/settings.*` | The settings of the web UI with their defaults and checks |
 | `logic/schedule.*` | When the display is on (night, clock, standby), from the settings |
-| `logic/bitmap_format.*` | 84 x 19 bitmap format, hex encoding, bitmap names |
+| `logic/bitmap_format.*` | 84 x 19 bitmap format, hex encoding, names of bitmaps, pages and fonts |
+| `logic/page.*` | Dynamic pages: the struct, checks, time slots, texts of the elements (clock, date, Home Assistant value, text) |
+| `logic/page_render.*` | Draws a dynamic page into a bitmap (display and web previews) |
+| `logic/font.*` | Dot font format (built-in and uploaded fonts), text width, drawing |
+| `logic/builtin_fonts.*` | Small, Normal, Large, Full height; the `.cpp` is generated by `tools/make_builtin_fonts.py` |
+| `logic/builtin_pages.*` | The built-in Clock page (the clock of the old firmware) |
 | `logic/power_timer.*` | Countdown to switching the display off |
 | `logic/status_led.h` | Blink pattern of the built-in LED |
 | `logic/boot_policy.*` | How to start after a reset: normal, OTA-only window, safe mode |
@@ -29,19 +34,24 @@ debug output. Wiring is described in the [main README](../../README.md#wiring-be
 | `system/system_store.*` | Settings in NVS: WiFi, recovery reason, firmware slot and version, power-on count |
 | `system/settings_store.*` | The web UI settings in NVS |
 | **`display/`** | **What is drawn** |
-| `display/frames.*` | The screens: clock, "No WiFi", page bitmap, live image, off image (`FlipdotFrames`) |
+| `display/frames.*` | The screens: dynamic page, "No WiFi", page bitmap, live image, off image (`FlipdotFrames`) |
 | `display/bitmap_store.*` | Built-in bitmaps and the uploaded ones on LittleFS |
+| `display/page_store.*` | Built-in and stored dynamic pages (`/pages/<name>.pg`) |
+| `display/font_store.*` | Built-in and uploaded fonts (`/fonts/<name>.fnt`) |
+| `display/page_resources.*` | Gives the page renderer its bitmaps, fonts and Home Assistant values |
 | `display/status_screen.*` | Two-line status messages at boot, after a crash and in the recovery app (`StatusScreen`) |
 | `display/text.*` | Centered text lines on the 84 x 19 display |
-| `display/bitmaps.h` | 1-bit bitmaps (Pikachu, thought bubble, Nintendo logo, ...) |
+| `display/bitmaps.h` | 1-bit bitmaps (Nintendo logo, Pikachu with the thought bubble, ...) |
 | **`nano_link/`** | **Connection to the Nano** |
 | `nano_link/nano_link.*` | Relay and serial link: power on (waits for `READY`), power off, bootloader start (`NanoLink`) |
 | `nano_link/nano_flash_bridge.*` | WiFi to serial bridge for flashing the Nano over WiFi (TCP port 2323) |
 | **`net/`** | **Network** |
 | `net/wifi_ota.*` | WiFi (with a restart when it stays down), ESP32 OTA updates, OTA-only mode |
 | `net/home_assistant.*` | MQTT and the Home Assistant entities (power switch, mode and off image dropdowns, IP and firmware sensors, recovery button) |
+| `net/ha_api.*` | Reads Home Assistant entity values over the REST API for the dynamic pages |
 | **`web/`** | **Web UI** (see the [main README](../../README.md#web-ui)) |
 | `web/web_ui.*` | Web server and JSON API (the endpoints are listed in `web_ui.h`) |
+| `web/page_json.*` | Dynamic pages as JSON |
 | `web/web_page.h` | The page: HTML and JavaScript; the browser converts images and draws the previews |
 
 `DisplayController` only talks to two small interfaces, `DisplayPower` (implemented by
@@ -127,8 +137,7 @@ Rules for changing the code:
 
 | Time | Display |
 |------|---------|
-| 08:00 – 17:00 | Pikachu and the clock, updated every minute |
-| 17:00 – 22:00 | Yawning Pikachu and the clock |
+| 08:00 – 22:00 | The page; the built-in Clock page shows Pikachu and the clock (yawning from 17:00), updated every minute |
 | 22:00 – 23:30 | Clock shown only during the minutes :00, :15, :30 and :45. In between the power is off, and the last time stays visible (flipdots keep their image without power). |
 | 23:31 – 08:00 | Screen cleared, power off after 30 s |