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/glm/gtc/epsilon.inl

@@ -0,0 +1,80 @@
+/// @ref gtc_epsilon
+
+// Dependency:
+#include "../vector_relational.hpp"
+#include "../common.hpp"
+
+namespace glm
+{
+	template<>
+	GLM_FUNC_QUALIFIER bool epsilonEqual
+	(
+		float const& x,
+		float const& y,
+		float const& epsilon
+	)
+	{
+		return abs(x - y) < epsilon;
+	}
+
+	template<>
+	GLM_FUNC_QUALIFIER bool epsilonEqual
+	(
+		double const& x,
+		double const& y,
+		double const& epsilon
+	)
+	{
+		return abs(x - y) < epsilon;
+	}
+
+	template<length_t L, typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER vec<L, bool, Q> epsilonEqual(vec<L, T, Q> const& x, vec<L, T, Q> const& y, T const& epsilon)
+	{
+		return lessThan(abs(x - y), vec<L, T, Q>(epsilon));
+	}
+
+	template<length_t L, typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER vec<L, bool, Q> epsilonEqual(vec<L, T, Q> const& x, vec<L, T, Q> const& y, vec<L, T, Q> const& epsilon)
+	{
+		return lessThan(abs(x - y), vec<L, T, Q>(epsilon));
+	}
+
+	template<>
+	GLM_FUNC_QUALIFIER bool epsilonNotEqual(float const& x, float const& y, float const& epsilon)
+	{
+		return abs(x - y) >= epsilon;
+	}
+
+	template<>
+	GLM_FUNC_QUALIFIER bool epsilonNotEqual(double const& x, double const& y, double const& epsilon)
+	{
+		return abs(x - y) >= epsilon;
+	}
+
+	template<length_t L, typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER vec<L, bool, Q> epsilonNotEqual(vec<L, T, Q> const& x, vec<L, T, Q> const& y, T const& epsilon)
+	{
+		return greaterThanEqual(abs(x - y), vec<L, T, Q>(epsilon));
+	}
+
+	template<length_t L, typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER vec<L, bool, Q> epsilonNotEqual(vec<L, T, Q> const& x, vec<L, T, Q> const& y, vec<L, T, Q> const& epsilon)
+	{
+		return greaterThanEqual(abs(x - y), vec<L, T, Q>(epsilon));
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER vec<4, bool, Q> epsilonEqual(qua<T, Q> const& x, qua<T, Q> const& y, T const& epsilon)
+	{
+		vec<4, T, Q> v(x.x - y.x, x.y - y.y, x.z - y.z, x.w - y.w);
+		return lessThan(abs(v), vec<4, T, Q>(epsilon));
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER vec<4, bool, Q> epsilonNotEqual(qua<T, Q> const& x, qua<T, Q> const& y, T const& epsilon)
+	{
+		vec<4, T, Q> v(x.x - y.x, x.y - y.y, x.z - y.z, x.w - y.w);
+		return greaterThanEqual(abs(v), vec<4, T, Q>(epsilon));
+	}
+}//namespace glm