Finch 2.4.0: methods, maps, errors as values; str() of any value; macOS and ARM64 docs; Kate support

- fn Struct.method(...) with self by reference, also on C structs
- map[K]V: insertion-ordered hash maps, literals, m[k] += 1, has/get/remove/keys/values
- -> T! / -> !, return error(...), or <value>, or { err }, try; fallible int/float/read_file/write_file/delete_file
- for i, x in list / for k, v in map
- print and str() share one text formatter
- LSP: method and map completion, method signatures; grammar and snippets for VS Code and Kate
- tests: 74 (methods, errors, maps + 11 failure cases); docs at all three levels, en and pl

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/run.sh

@@ -27,7 +27,8 @@ for f in run/*.fch; do
     if [ "${MEMCHECK:-0}" = 1 ]; then
         exe="$tmp/$(basename "${f%.fch}")"
         "$FINCH" build "$f" -o "$exe" >/dev/null 2>&1
-        if ! valgrind -q --leak-check=full --errors-for-leak-kinds=all --error-exitcode=99 "$exe" < "$input" >/dev/null 2>"$tmp/vg"; then
+        valgrind -q --leak-check=full --errors-for-leak-kinds=all --error-exitcode=99 "$exe" < "$input" >/dev/null 2>"$tmp/vg"
+        if [ $? -eq 99 ]; then  # (other exit codes are the program's own)
             failed=$((failed + 1))
             echo "MEMCHECK FAIL $f"
             head -20 "$tmp/vg"