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/methods.out

@@ -0,0 +1,10 @@
+clicks: 7 [3, 2, 2] 7
+clicks: 7 [3, 2, 2]
+copy: 17 [3, 2, 2, 10]
+clicks: 14 [3, 2, 2, 3, 2, 2]
+a: 0 [0] | b: 8 [7, 1]
+temp: 5 []
+6
+24 23
+10
+25