Vector types (SIMD): f32x8, i8x32, f64x4 and the rest; --cpu native

- fNxM / iNxM / uNxM up to 512 bits, as LLVM vectors (<8 x float>): LLVM picks SSE, AVX2,
  AVX-512 or NEON for them
- f32x8(x) in every lane, f32x8(a, ..., h), f32x8(list, i) loads, f32x8(i32x8 v) converts
- + - * / and the bit operators lane by lane, with a plain number on either side counting for every lane;
  v[i], v[i] = x, v.len, == / != (every lane), print and str
- methods: sum min max dot abs sqrt floor ceil round fma store; min/max/abs/clamp lane by lane
- wide vectors (and structs holding them) are loaded and stored with align 16, what malloc and the stack give
- --cpu <name> (and cpu = "..." in finch.toml): native, x86-64-v3, apple-m1, ...
- debug info shows vectors; the language server completes their methods; Kate and VS Code highlight them
- f32 x = -1.5 works: a minus in front of a float written in the code keeps it such a number

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Psc42moPLwP43Cmb9oZqSR

editors/vscode/test/grammar.js

@@ -29,6 +29,7 @@ const code = [
   'test "lives \\(hp + f(1)) left" {',
   '    assert(clamp(x, 0, 9) == 3)',
   '}',
+  'fn dot(f32x8 a, i8x32 b) {',
 ];
 const expect = [  // [line, token text, scope that must be present]
   [0, 'import', 'keyword.control.import'], [0, '"stdio.h"', 'string.quoted.double'],
@@ -49,6 +50,7 @@ const expect = [  // [line, token text, scope that must be present]
   [17, 'test', 'keyword.other.test'], [17, '\\(', 'punctuation.section.embedded.begin'], [17, 'hp', 'meta.embedded.line'],
   [17, 'f', 'meta.embedded.line'], [17, 'left', 'string.quoted.double'],
   [18, 'assert', 'support.function.builtin'], [18, 'clamp', 'support.function.builtin'],
+  [20, 'f32x8', 'storage.type.primitive'], [20, 'i8x32', 'storage.type.primitive'],
 ];
 registry.loadGrammar('source.finch').then((g) => {
   let state = vsctm.INITIAL, toks = [];