The compiler is written in Finch, and nothing else: src/*.fch, built from a seed

boot/ is src/ now. The C++ compiler and CMake are gone from this branch (they are on before-bootstrap).
bootstrap/build.sh builds the compiler from bootstrap/<system>.ll -- the compiler's own LLVM IR -- then builds
it with itself and checks the two come out identical. bootstrap/build.sh seed writes the seed anew.

The driver is complete: the runtime is compiled once and kept in ~/.cache/finch; a program's own C files,
.o and .a files and frameworks link along; a linker failure is read and answered with  link "lib"  or the
library that is missing. The old tests/fail diagnostics are all in again (a missing import, a str compared with
null, 'write just the library's name', a map key that is a float, non-ASCII names, ...).

tests/run.sh is the one test runner: programs, refusals, -g builds and the shared library. 106 passed.

shell.nix

@@ -4,10 +4,7 @@ pkgs.mkShell {
   packages = with pkgs; [
     # building Finch (the clang wrapper first, so `clang` finds the system headers)
     llvmPackages.clang
-    llvmPackages.llvm
     llvmPackages.libclang   # reads C headers for `import "stdio.h"`
-    cmake
-    ninja
     pkg-config              # finds the right flags for `link "..."`
 
     # for the graphics examples (window, opengl, raylib, vulkan)