refactor(js/ts/python): use struct partial active patterns and postfix array syntax

[fable-repo-assist]

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Summary

Fixes code scanning alerts from Ionide.Analyzers (IONIDE-009 and IONIDE-002):

• IONIDE-009 (alerts Docs: Provide guidance for fable nuget publish #1056, reraise doesn't work correctly in JS #1057, Support String.Join with objects #1058, Prevent dotnet template engine to parse Paket.Restore.targets #1069, Fable Simple Template dotnet-fable require manual installation of several missing package dependencies when the user .nuget and .dotnet directories does not exists or empty #1070, Implement isDaylightSavingTime #1083): Add [<return: Struct>] to partial active patterns in BabelPrinter.fs and Python transform files. This avoids heap allocation for the option return type, since the patterns return simple values (unit, string, or tuples) that benefit from ValueOption struct representation.

• IONIDE-002 (alerts Repl target fix #1065, Curried Applicative issue #1072, Is it possible to emit an error when RegexOptions.Singleline is used? #1181): Replace C#-style [] postfix syntax with idiomatic F# array postfix syntax in BabelPrinter.fs, Fable2Python.Util.fs, and Python.AST.fs.

Files Changed

File	Change
src/Fable.Transforms/BabelPrinter.fs	[<return: Struct>] on UndefinedOrVoid, NullOrUndefinedOrVoid, StringConstant; TypeParameter array
src/Fable.Transforms/Python/Fable2Python.Util.fs	[<return: Struct>] on Function, IEnumerableOfKeyValuePair; Fable.Ident array
src/Fable.Transforms/Python/Fable2Python.Transforms.fs	[<return: Struct>] on UsePattern
src/Fable.Transforms/Python/Python.AST.fs	byte array

Notes

These are purely cosmetic/performance changes with no semantic impact. Struct partial active patterns work identically in match expressions; callers do not need to change.

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[github-actions]

Python Type Checking Results (Pyright)

Metric	Value
Total errors	33
Files with errors	4
Excluded files	4
New errors	✅ No

Excluded files with errors (4 files)

These files have known type errors and are excluded from CI. Remove from pyrightconfig.ci.json as errors are fixed.

File	Errors	Status
temp/tests/Python/test_hash_set.py	18	Excluded
temp/tests/Python/test_applicative.py	12	Excluded
temp/tests/Python/test_nested_and_recursive_pattern.py	2	Excluded
temp/tests/Python/fable_modules/thoth_json_python/encode.py	1	Excluded