feature: hud (#37)

* build: replace FetchContent with direct includes for glm

* build(deps): replace SOIL2 with stb for image and vorbis decoding

* build: replace FetchContent with direct includes for toml++

* refactor(texture): bump block texture size to 512 and disable items tab

* feat: add hotbar system with ItemStack and RowLayout

* fix(ui): restrict Ctrl key handling to typing mode

* feat(ui): add widget border support and highlight selected hotbar slot

* fix(ui): update borders on scale change and correct Image width

- Added update_border() calls in set_scale() for Button, ChatBox, Image, Label, and TextField.
- Fixed Image::width() to multiply by width instead of height.
- Added early return in Widget::update_border() if border is not supported.

* feat(ui): add border visual feedback on slider drag

* feat(ui): add ItemSlot widget and refactor hotbar to use it

* feat(world_scene): add inventory UI and pause type enum

* feat(ui): add item slot tooltip and make window size static

* fix(ui label): account for background offset in width/height

* refactor(ui): centralize item info label in inventory and add update

* feat(ui): add hotbar interaction in inventory UI

* fix(inventory-ui): correct row creation logic for first item

The loop starting at index 0 created a new row on the first iteration
(i % 10 == 0). Shift the loop to start at 1 and adjust modulus condition
to create rows correctly every 10 items.

* feat(block): add name_key for localized block names

Add `name_key` field to all block TOML definitions, enabling per-block localization. Update `BlockData` struct and `BlockManager` with `local_name()` method that returns a localized string via the translation system. Add corresponding entries to `en_US.json` and `zh_CN.json`. Modify inventory UI to use the localized name when displaying block info, and fix a bug where emptying a hotbar slot did not clear the item locally.

* fix(ui): change inventory item slot color from white to gray

* fix(ui): add missing include for std::array

include/toml++/impl/std_string.hpp

@@ -0,0 +1,53 @@
+//# This file is a part of toml++ and is subject to the the terms of the MIT license.
+//# Copyright (c) Mark Gillard <mark.gillard@outlook.com.au>
+//# See https://github.com/marzer/tomlplusplus/blob/master/LICENSE for the full license text.
+// SPDX-License-Identifier: MIT
+#pragma once
+
+#include "preprocessor.hpp"
+TOML_DISABLE_WARNINGS;
+#include <string_view>
+#include <string>
+TOML_ENABLE_WARNINGS;
+
+#if TOML_DOXYGEN                                                                                                       \
+	|| (defined(__cpp_char8_t) && __cpp_char8_t >= 201811 && defined(__cpp_lib_char8_t)                                \
+		&& __cpp_lib_char8_t >= 201907)
+#define TOML_HAS_CHAR8 1
+#else
+#define TOML_HAS_CHAR8 0
+#endif
+
+/// \cond
+
+namespace toml // non-abi namespace; this is not an error
+{
+	using namespace std::string_literals;
+	using namespace std::string_view_literals;
+}
+
+#if TOML_ENABLE_WINDOWS_COMPAT
+
+TOML_IMPL_NAMESPACE_START
+{
+	TOML_NODISCARD
+	TOML_EXPORTED_FREE_FUNCTION
+	std::string narrow(std::wstring_view);
+
+	TOML_NODISCARD
+	TOML_EXPORTED_FREE_FUNCTION
+	std::wstring widen(std::string_view);
+
+#if TOML_HAS_CHAR8
+
+	TOML_NODISCARD
+	TOML_EXPORTED_FREE_FUNCTION
+	std::wstring widen(std::u8string_view);
+
+#endif
+}
+TOML_IMPL_NAMESPACE_END;
+
+#endif // TOML_ENABLE_WINDOWS_COMPAT
+
+/// \endcond