Localize remaining hardcoded UI strings and persist language preference

Replaces the last hardcoded English strings (initial-scene modals, game
menu save status messages) with locale-loaded text, adds a shared
LOCALE_LIST so the settings dropdown and locale manager stay in sync,
and persists the chosen language into savemeta_t across all platforms.
Also fixes two message buffers that were too small for their longest
translations.

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

src/dusklinux/save/savejsonlinux.h

@@ -42,6 +42,13 @@ void saveJsonWriterAddFloatLinux(
   savejsonwriterlinux_t *writer, const char_t *key, const float_t value
 );
 
+/**
+ * Adds a "key": <uint> field to the root object.
+ */
+void saveJsonWriterAddUInt8Linux(
+  savejsonwriterlinux_t *writer, const char_t *key, const uint8_t value
+);
+
 /**
  * Adds a string field to the root object. The value is copied into the
  * document, so the caller's buffer doesn't need to outlive the call.
@@ -120,6 +127,14 @@ float_t saveJsonReadFloatLinux(
   yyjson_val *root, const char_t *key, const float_t defaultValue
 );
 
+/**
+ * Reads a uint8 field, falling back to defaultValue if the key is
+ * missing or not a number.
+ */
+uint8_t saveJsonReadUInt8Linux(
+  yyjson_val *root, const char_t *key, const uint8_t defaultValue
+);
+
 /**
  * Reads a string field into out, falling back to defaultValue if the key
  * is missing or not a string. Always null-terminates.