Compiler and docs on every system: macOS Intel in CI, releases made by CI, docs for vectors and --cpu

- CI: macOS on Apple Silicon and Intel (macos-15, macos-15-intel); a tag v* attaches every package
  (Linux x64/ARM64, macOS ARM64/x64, Windows x64, the VS Code extension) to its release
- vectors: fma is llvm.fmuladd (llvm.fma was a libm call per lane without FMA hardware: 3.5x slower)
- examples/simd.fch: a dot product eight at a time, timed against the plain loop
- README and the English guides: installing on Linux, macOS and Windows; vectors (SIMD); --cpu;
  -g is DWARF on Windows too (lldb from llvm-mingw); no more mention of the C++ compiler
- comments left from the C++ compiler (src/target.cpp, src/codegen.cpp, "never frees") brought up to date

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

docs/en/for-beginners.md

@@ -53,8 +53,9 @@ The computer reads your program from top to bottom, line by line.
 
 ## 2. Getting Finch ready
 
-Finch runs on **Linux** computers. If a teacher, parent or friend has already set it up
-for you, skip to the next section.
+Finch runs on **Linux**, **macOS** and **Windows** computers. If a teacher, parent or friend has already set it up
+for you, skip to the next section. (On a Mac or on Windows, ask someone to follow the
+[guide for technicians](for-technicians.md#2-installing): it has a ready-made Finch for both.)
 
 Otherwise, open the **Terminal** program (a window where you type commands) and type
 these lines one by one, pressing **Enter** after each:
@@ -76,7 +77,7 @@ To check it works, type:
 ./build/finch version
 ```
 
-You should see something like `Finch 2.5.0`.
+You should see something like `Finch 2.6.0`.
 
 ---