feat(kotlin-compose): design system + 33 components + gallery_kt + e2e android emulator + scaffolder fixes

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cpp/functions/gfx/sprite_batch.h

@@ -0,0 +1,43 @@
+#pragma once
+
+// sprite_batch — batched textured quad renderer on top of sokol_gfx.
+// Single draw call per atlas binding. Issue 0072b runtime gamedev.
+
+#include "sokol_gfx.h"
+#include "math2d.h"
+
+namespace fn::gfx {
+
+struct SpriteBatch {
+    sg_pipeline pipeline{};
+    sg_buffer   vbo{};
+    sg_view     current_view{};        // texture view bound this batch
+    sg_sampler  sampler{};
+    void*       cpu_buffer = nullptr;  // Vertex* on heap
+    int         cpu_capacity_quads = 0;
+    int         cpu_count_quads = 0;
+    float       proj[16]{};            // current view-proj matrix (column-major)
+    bool        in_pass = false;
+    bool        ok = false;
+};
+
+// Create the batcher. Allocates CPU buffer + sokol resources. cpu_capacity_quads
+// caps the per-flush quads (auto-flush when reached). Default 4096.
+SpriteBatch sprite_batch_create(int cpu_capacity_quads = 4096);
+void sprite_batch_destroy(SpriteBatch& b);
+
+// Begin a batch with a column-major 4x4 view-projection.
+// Call between sg_begin_pass and sg_end_pass.
+void sprite_batch_begin(SpriteBatch& b, const float view_proj_col_major[16]);
+
+// Queue one textured quad. dst is the screen rect. src is the UV rect inside the
+// texture, in pixels (0..image_size). tint multiplies the texture sample.
+// view must be a sg_view created with sg_make_view({.texture.image = ...}).
+void sprite_batch_draw(SpriteBatch& b, sg_view view, int img_w, int img_h,
+                       fn::math2d::Rect src, fn::math2d::Rect dst,
+                       fn::math2d::Color tint = fn::math2d::Color::white());
+
+// Flush remaining quads.
+void sprite_batch_end(SpriteBatch& b);
+
+}  // namespace fn::gfx