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/errors.out

@@ -0,0 +1,19 @@
+80
+-1
+-1
+Config(name: "web", port: 80)
+Config(name: "db", port: 5432)
+skipped: expected name=port, got 'bad'
+skipped: the port 'y' is not a number
+skipped: the port 70000 is out of range
+12 7 0 2.5 -1
+default text
+read failed: true
+save failed: no file name
+saved
+second delete failed
+not enough money: 70 < 500
+70
+42 -1
+443
+error: the port 'not a port' is not a number