Initial commit: Odin editor client + Kotlin daemon prototype

Native SDL3 editor written in Odin with a piece-table buffer core,
backed by a Kotlin/JVM daemon speaking newline-delimited JSON over
localhost TCP for Gradle import, Kotlin/Java diagnostics, and
heuristic completion/hover/definition/references/rename.

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

client/odin/shaders/rect.frag.glsl

@@ -0,0 +1,8 @@
+#version 450
+
+layout(location = 0) in vec4 v_color;
+layout(location = 0) out vec4 out_color;
+
+void main() {
+    out_color = v_color;
+}

client/odin/shaders/rect.vert.glsl

@@ -0,0 +1,17 @@
+#version 450
+
+layout(location = 0) in vec2 a_pos;
+layout(location = 1) in vec4 a_color;
+
+layout(set = 1, binding = 0) uniform VertexUniforms {
+    vec2 u_viewport;
+};
+
+layout(location = 0) out vec4 v_color;
+
+void main() {
+    vec2 ndc = vec2((a_pos.x / u_viewport.x) * 2.0 - 1.0,
+                   1.0 - (a_pos.y / u_viewport.y) * 2.0);
+    gl_Position = vec4(ndc, 0.0, 1.0);
+    v_color = a_color;
+}

client/odin/shaders/text.frag.glsl

@@ -0,0 +1,12 @@
+#version 450
+
+layout(location = 0) in vec2 v_uv;
+layout(location = 1) in vec4 v_color;
+layout(location = 0) out vec4 out_color;
+
+layout(set = 2, binding = 0) uniform sampler2D u_font;
+
+void main() {
+    float alpha = texture(u_font, v_uv).r;
+    out_color = vec4(v_color.rgb, v_color.a * alpha);
+}

client/odin/shaders/text.vert.glsl

@@ -0,0 +1,20 @@
+#version 450
+
+layout(location = 0) in vec2 a_pos;
+layout(location = 1) in vec2 a_uv;
+layout(location = 2) in vec4 a_color;
+
+layout(set = 1, binding = 0) uniform VertexUniforms {
+    vec2 u_viewport;
+};
+
+layout(location = 0) out vec2 v_uv;
+layout(location = 1) out vec4 v_color;
+
+void main() {
+    vec2 ndc = vec2((a_pos.x / u_viewport.x) * 2.0 - 1.0,
+                   1.0 - (a_pos.y / u_viewport.y) * 2.0);
+    gl_Position = vec4(ndc, 0.0, 1.0);
+    v_uv = a_uv;
+    v_color = a_color;
+}