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>

editors/vscode/package.json

@@ -2,7 +2,7 @@
   "name": "finch-lang",
   "displayName": "Finch",
   "description": "The Finch programming language: highlighting, errors as you type, completion, hover, go to definition, and a Run button.",
-  "version": "2.3.0",
+  "version": "2.4.0",
   "publisher": "nexoniarz",
   "license": "Apache-2.0",
   "icon": "images/icon.png",