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/display/bitmap_store.cpp

@@ -15,6 +15,8 @@ struct BuiltinBitmap
 
 static const BuiltinBitmap BUILTIN[] = {
 	{"Nintendo", nintendo_bitmap_Nintendo_new},
+	{"Pikachu", pikachu_clock_bitmap},
+	{"Pikachu yawning", pikachu_yawning_clock_bitmap},
 };
 
 static bool mounted = false;
@@ -36,8 +38,9 @@ static String path(const char *name)
 bool bitmapStoreBegin()
 {
 	mounted = LittleFS.begin(true);
-	if (mounted && !LittleFS.exists(DIR))
-		LittleFS.mkdir(DIR);
+	for (const char *dir : {DIR, "/pages", "/fonts"})
+		if (mounted && !LittleFS.exists(dir))
+			LittleFS.mkdir(dir);
 	Serial.printf("Bitmap storage %s\n", mounted ? "ready" : "not available (old flash layout?)");
 	return mounted;
 }
@@ -53,27 +56,37 @@ void bitmapStorageUsage(size_t &used, size_t &total)
 	total = mounted ? LittleFS.totalBytes() : 0;
 }
 
-std::vector<BitmapInfo> listBitmaps()
+std::vector<String> storedNames(const char *dir_path, const char *extension)
 {
-	std::vector<BitmapInfo> list;
-	for (const BuiltinBitmap &b : BUILTIN)
-		list.push_back({b.name, true});
+	std::vector<String> names;
 	if (!mounted)
-		return list;
-
-	File dir = LittleFS.open(DIR);
+		return names;
+	File dir = LittleFS.open(dir_path);
+	if (!dir)
+		return names;
 	for (File file = dir.openNextFile(); file; file = dir.openNextFile())
 	{
 		String name = file.name();
 		int slash = name.lastIndexOf('/');
 		if (slash >= 0)
 			name = name.substring(slash + 1);
-		if (!name.endsWith(".bin"))
+		if (!name.endsWith(extension))
 			continue;
-		name.remove(name.length() - 4);
-		if (validBitmapName(name.c_str()) && !builtin(name.c_str()))
-			list.push_back({name, false});
+		name.remove(name.length() - strlen(extension));
+		if (validBitmapName(name.c_str()))
+			names.push_back(name);
 	}
+	return names;
+}
+
+std::vector<BitmapInfo> listBitmaps()
+{
+	std::vector<BitmapInfo> list;
+	for (const BuiltinBitmap &b : BUILTIN)
+		list.push_back({b.name, true});
+	for (const String &name : storedNames(DIR, ".bin"))
+		if (!builtin(name.c_str()))
+			list.push_back({name, false});
 	return list;
 }