Weather forecast page, 16 elements per page, attribute paths, examples from the display

- Home Assistant attributes can be paths into lists (forecast.1.condition).
- Date elements can show a day ahead (day offset 0-7).
- Pages hold 16 elements (page format 6; the old formats are frozen at 8).
  Pages are reset in place (clearPage), not through a 4 KB temporary.
- Verwachting page: today (icon, temperature, max/min) and the next 2
  days with 7 x 7 icons (weer7 <condition>), from a template sensor
  (docs/home-assistant.md).
- examples/home-pages.json is exported from the display with all pages
  and their icons, private entity id parts replaced by placeholders
  (tools/export_examples.py replaces tools/make_example_pages.py).

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

src/esp32/net/ha_api.cpp

@@ -57,7 +57,7 @@ static String token;
 static char plex_user[PLEX_USER_SIZE] = "";
 static std::vector<Entry> entries;
 // Kept for the editor's previews, besides the watched ones
-static const size_t MAX_ENTRIES = 24;
+static const size_t MAX_ENTRIES = 32;
 
 static QueueHandle_t requests = nullptr;
 static QueueHandle_t responses = nullptr;
@@ -74,6 +74,46 @@ static uint32_t preview_done_at = 0;
 // The task
 // ---------------------------------------------------------------------------
 
+// Attributes can be a path into lists and objects: "forecast.1.condition" is the condition
+// of the second forecast. One part of it (up to the next dot) goes into `part`; returns the
+// rest, nullptr after the last part.
+static const char *nextPart(const char *path, char *part, size_t size)
+{
+	size_t n = strcspn(path, ".");
+	strlcpy(part, path, n + 1 < size ? n + 1 : size);
+	return path[n] == '.' ? path + n + 1 : nullptr;
+}
+
+static bool isIndex(const char *part)
+{
+	if (!part[0])
+		return false;
+	for (const char *c = part; *c; c++)
+		if (!isdigit((unsigned char)*c))
+			return false;
+	return true;
+}
+
+// Only the path is kept from the answer. List indexes become [0]: ArduinoJson applies the
+// first element of a filter list to all elements.
+static void addFilter(JsonVariant f, const char *path)
+{
+	char part[ELEMENT_ATTRIBUTE_SIZE];
+	const char *rest = nextPart(path, part, sizeof(part));
+	if (isIndex(part))
+	{
+		JsonVariant element = f.to<JsonArray>().add<JsonVariant>();
+		if (rest)
+			addFilter(element, rest);
+		else
+			element.set(true);
+	}
+	else if (rest)
+		addFilter(f[(const char *)part].to<JsonVariant>(), rest); // char arrays would be taken as literals
+	else
+		f[(const char *)part] = true;
+}
+
 // Blocks at most about 2 x HA_HTTP_TIMEOUT (connect, then the answer)
 static const char *fetch(const Request &r, char *value, size_t value_size)
 {
@@ -99,7 +139,7 @@ static const char *fetch(const Request &r, char *value, size_t value_size)
 
 	JsonDocument filter;
 	if (r.attribute[0])
-		filter["attributes"][(const char *)r.attribute] = true; // a char array would be taken as a literal of 32 characters
+		addFilter(filter["attributes"].to<JsonVariant>(), r.attribute);
 	else
 		filter["state"] = true;
 	JsonDocument doc;
@@ -110,7 +150,15 @@ static const char *fetch(const Request &r, char *value, size_t value_size)
 
 	JsonVariantConst v = doc["state"];
 	if (r.attribute[0])
-		v = doc["attributes"][(const char *)r.attribute];
+	{
+		v = doc["attributes"];
+		char part[ELEMENT_ATTRIBUTE_SIZE];
+		for (const char *path = r.attribute; path && !v.isNull();)
+		{
+			path = nextPart(path, part, sizeof(part));
+			v = isIndex(part) ? v[(size_t)atoi(part)] : v[(const char *)part];
+		}
+	}
 	if (v.isNull())
 		return "Unknown attribute";
 	String text;