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>

CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.20)
-project(finch VERSION 2.3.0 LANGUAGES C CXX)  # C: LLVM's CMake config checks C headers on some systems
+project(finch VERSION 2.4.0 LANGUAGES C CXX)  # C: LLVM's CMake config checks C headers on some systems
 
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
@@ -15,6 +15,7 @@ add_executable(finch
     src/codegen.cpp
     src/codegen_types.cpp
     src/codegen_builtins.cpp
+    src/codegen_map.cpp
     src/abi.cpp
     src/cimport.cpp
     src/target.cpp