Build each screen in one language: the screen texts from the translations, European letters in the fonts, and Language & region in the app

The firmware takes its texts from screen_manager/translations/<code>.json at build time (components/smart_display:
one table in main.cpp, keys in screen_text_keys.h), and the fonts carry every letter European languages write with.
The app keeps Settings -> Language & region (language, clock, numbers) for every screen, writes LANGUAGE into the
screens' YAML and sends the clock and the number format in the layout message; the per-screen 24-hour clock goes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

components/smart_display/runtime_model.h

@@ -5,6 +5,7 @@
 #include <string>
 #include <utility>
 #include <vector>
+#include "screen_text.h"
 #include <cmath>
 #include <cstdint>
 #include <cstdlib>
@@ -429,7 +430,7 @@ struct Model {
   // Pages the manager wants shown even when the last ones are still empty (0.2.26+).
   uint8_t pages = 1;
   size_t count = 0;
-  std::string title = "Choose tiles in HA";
+  std::string title = screen_text::tr(screen_text::txt::status_choose_tiles);
   bool configured = false;
   // Why the last set_layout refused a layout, for the manager's inbox status; empty when it took the layout or the
   // message itself was wrong (the status then says "invalid message", as before).
@@ -469,7 +470,7 @@ struct Model {
       return false;
     }
     // A title-only update must not interrupt an open control card.
-    title = name.empty() ? "Home" : name;
+    title = name.empty() ? std::string(screen_text::tr(screen_text::txt::status_home)) : name;
     if (changed) {
       // Freed before the new list is made, so the heap never holds both.
       tiles.clear();