finch.toml, threads and atomics, finch fmt, C++ files, struct #defines, a struct variable given for its ptr

- finch.toml: name, entry, paths, include, links, libdirs, cflags, ldflags, and [target.windows] etc.;
  finch run / build / test with no file use its entry
- import thread: spawn, join, mutex, cpus; atomic_add/sub/load/store/swap/cas built in
- finch fmt [--check]: indentation by { }, trailing spaces, empty lines; also as LSP formatting
- link "x.cpp" (or in finch.toml): built with the C++ compiler, which then links (FINCH_CXX)
- #define RAYWHITE (Color){ 245, 245, 245, 255 } imports as a Color
- push(body) where push takes ptr[Body]: the same as push(addr(body))
- --target android (NDK clang from ANDROID_NDK_HOME, -llog)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016GzNP6r8dg6WDxUVZy8wjL

tests/new/cunion.h

@@ -22,6 +22,14 @@ typedef struct { int kind; union { int i; float f; } as; } Tagged;
 #define LONG_NAME "a" "b"
 #define NOT_A_CONSTANT do { } while (0)
 
+typedef struct { unsigned char r, g, b, a; } Color;
+typedef struct { float x, y; } Vec2;
+#define CLITERAL(type) (type)
+#define RAYWHITE CLITERAL(Color){ 245, 245, 245, 255 }
+#define DARK (Color){ 20, 20, 20 }
+#define HALF_UP (Vec2){ 0.5f, -1 }
+#define NOT_A_STRUCT_CONST (Color){ 1, 2, (unsigned char)(long)&poll_event, 4 }
+
 static inline int fill_key(Event *e, int key) {
     e->key.type = EV_KEY;
     e->key.key = key;