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

src/docs.fch

@@ -26,6 +26,12 @@ fn builtins() -> []Doc {
         doc("max", "max(a, b, ...) -> number", "The biggest of the numbers, in the type they all fit."),
         doc("abs", "abs(x) -> number", "x without its minus sign (any number type)."),
         doc("clamp", "clamp(x, lo, hi) -> number", "x, but at least lo and at most hi."),
+        doc("atomic_add", "atomic_add(ptr[int] p, n) -> int", "Adds n to the number at p in one step other threads can't split; gives back what was there before."),
+        doc("atomic_sub", "atomic_sub(ptr[int] p, n) -> int", "Takes n from the number at p in one step; gives back what was there before."),
+        doc("atomic_load", "atomic_load(ptr[int] p) -> int", "Reads the number at p, as another thread last wrote it."),
+        doc("atomic_store", "atomic_store(ptr[int] p, n)", "Writes n to p so other threads see it whole."),
+        doc("atomic_swap", "atomic_swap(ptr[int] p, n) -> int", "Puts n at p and gives back what was there, in one step."),
+        doc("atomic_cas", "atomic_cas(ptr[int] p, old, new) -> bool", "Puts new at p only if old is there (compare and swap); true if it did."),
         doc("addr", "addr(x) -> ptr[T]", "A pointer to a variable, field or element. addr(function) gives C a callback."),
         doc("new", "new(value) -> ptr[T]", "Puts a copy of the value on the heap. Give it back with free(...)."),
         doc("free", "free(ptr p)", "Gives back memory from new(...) (or from C), freeing what the value owns."),