Home Assistant requests in a task, progress bar, Plex page, bitmap cache

- net/ha_api: the HTTP requests run in a FreeRTOS task on core 0; loop()
  only hands over copies through queues. The web UI's test button polls.
  No more 3-4 s loop() stalls once a minute; timeout raised to 5 s.
- Progress bar page element (page format 4, v3 pages are converted)
- Plex user setting (settings v6): {plex_user} in entity ids
- Plex page (examples): watchers, play/pause icon, title, progress
- Bitmaps cached in RAM: a LittleFS read took ~100 ms on every render
  and web preview; long JSON lists sent in 2 KB pieces
- Backup includes the refresh settings and the Plex user

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

src/esp32/display/bitmap_store.cpp

@@ -1,6 +1,7 @@
 #include "display/bitmap_store.h"
 
 #include <LittleFS.h>
+#include <map>
 #include <strings.h>
 
 #include "display/bitmaps.h"
@@ -22,6 +23,18 @@ static const BuiltinBitmap BUILTIN[] = {
 static bool mounted = false;
 static uint32_t revision = 0;
 
+// Bitmaps read before, also the names that don't exist (images try a name per state, then
+// "default"). Reading one from LittleFS takes about 100 ms, and pages are drawn again for
+// every frame (scrolling, seconds) and for every preview in the web UI. Cleared when a
+// bitmap is saved or deleted, and when it holds CACHE_MAX names.
+struct CachedBitmap
+{
+	bool exists;
+	uint8_t data[BITMAP_BYTES];
+};
+static std::map<String, CachedBitmap> cache;
+static const size_t CACHE_MAX = 64;
+
 static const BuiltinBitmap *builtin(const char *name)
 {
 	for (const BuiltinBitmap &b : BUILTIN)
@@ -99,7 +112,8 @@ bool bitmapExists(const char *name)
 {
 	if (builtin(name))
 		return true;
-	return mounted && validBitmapName(name) && LittleFS.exists(path(name));
+	uint8_t bitmap[BITMAP_BYTES];
+	return loadBitmap(name, bitmap); // through the cache
 }
 
 bool loadBitmap(const char *name, uint8_t *bitmap)
@@ -110,14 +124,33 @@ bool loadBitmap(const char *name, uint8_t *bitmap)
 		memcpy_P(bitmap, b->data, BITMAP_BYTES);
 		return true;
 	}
+	if (!mounted || !validBitmapName(name))
+		return false;
+	auto cached = cache.find(name);
+	if (cached != cache.end())
+	{
+		if (cached->second.exists)
+			memcpy(bitmap, cached->second.data, BITMAP_BYTES);
+		return cached->second.exists;
+	}
+
 	// Checked first: open() logs an error for a missing file (images try names by state)
-	if (!mounted || !validBitmapName(name) || !LittleFS.exists(path(name)))
-		return false;
-	File file = LittleFS.open(path(name), "r");
-	if (!file)
-		return false;
-	bool ok = file.read(bitmap, BITMAP_BYTES) == (size_t)BITMAP_BYTES;
-	file.close();
+	bool ok = false;
+	if (LittleFS.exists(path(name)))
+	{
+		File file = LittleFS.open(path(name), "r");
+		if (file)
+		{
+			ok = file.read(bitmap, BITMAP_BYTES) == (size_t)BITMAP_BYTES;
+			file.close();
+		}
+	}
+	if (cache.size() >= CACHE_MAX)
+		cache.clear();
+	CachedBitmap &entry = cache[name];
+	entry.exists = ok;
+	if (ok)
+		memcpy(entry.data, bitmap, BITMAP_BYTES);
 	return ok;
 }
 
@@ -138,6 +171,7 @@ const char *saveBitmap(const char *name, const uint8_t *bitmap)
 	bool ok = file.write(bitmap, BITMAP_BYTES) == (size_t)BITMAP_BYTES;
 	file.close();
 	revision++;
+	cache.clear();
 	return ok ? nullptr : "Storage full";
 }
 
@@ -150,5 +184,6 @@ const char *deleteBitmap(const char *name)
 	if (!LittleFS.remove(path(name)))
 		return "Could not delete the file";
 	revision++;
+	cache.clear();
 	return nullptr;
 }