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/web/page_json.cpp

@@ -73,6 +73,7 @@ void pageToJson(const DynamicPage &page, JsonObject out)
 		o["bar_height"] = e.bar_height;
 		o["bar_max"] = e.bar_max;
 		o["bar_frame"] = e.bar_frame;
+		o["day_offset"] = e.day_offset;
 	}
 }
 
@@ -89,7 +90,7 @@ static bool copyText(JsonVariantConst value, char *out, size_t size)
 
 const char *pageFromJson(JsonVariantConst in, DynamicPage &page)
 {
-	page = DynamicPage();
+	clearPage(page);
 	JsonArrayConst slots = in["slots"];
 	JsonArrayConst elements = in["elements"];
 	if (slots.size() > (size_t)PAGE_SLOTS)
@@ -136,6 +137,7 @@ const char *pageFromJson(JsonVariantConst in, DynamicPage &page)
 		e.bar_height = constrain(o["bar_height"] | 3, 0, 255);
 		e.bar_max = o["bar_max"] | 100.0f;
 		e.bar_frame = o["bar_frame"] | true;
+		e.day_offset = constrain(o["day_offset"] | 0, -1, DAY_OFFSET_MAX + 1); // out of range: validatePage says so
 		if (!copyText(o["map"], e.map, sizeof(e.map)))
 			return "The list of texts is too long (63 characters)";
 		const char *target = o["target"] | "";