[Repo Assist] feat(stdlib): add re (regular expressions) module bindings

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Summary

Adds F# bindings for Python's [re]((docs.python.org/redacted) (regular expressions) module — one of the most widely used stdlib modules, and a gap identified in the repo's future work notes.

Component	What's bound
Match	group(), groups(), groupdict(), start(), end(), span(), expand(), string, pos, endpos, lastindex, lastgroup
Pattern	match(), search(), fullmatch(), findall(), finditer(), sub(), subn(), split(), pattern, flags, groups, groupindex
Module functions	compile, match, search, fullmatch, findall, finditer, sub, subn, split, escape, purge
Flags module	IGNORECASE/I, MULTILINE/M, DOTALL/S, ASCII/A, LOCALE/L, UNICODE/U, VERBOSE/X, NOFLAG

Usage example

open Fable.Python.Regex

// Simple match
let m = re.``match`` ("([a-z]+) ([0-9]+)", "hello 42")
match m with
| None -> printfn "no match"
| Some m ->
    m.group ()        // "hello 42"
    m.group 1         // Some "hello"
    m.group 2         // Some "42"
    m.span ()         // (0, 8)

// Compiled pattern (efficient for repeated use)
let pat = re.compile ("[0-9]+", Flags.IGNORECASE)
let results = pat.findall "there are 3 cats and 42 dogs"
// ["3"; "42"]

// Substitution
re.sub ("[aeiou]", "*", "hello world")  // "h*ll* w*rld"

// Split
re.split (@"\s+", "a  b   c")  // [|"a"; "b"; "c"|]

Files changed

• src/stdlib/Regex.fs — new bindings (module Fable.Python.Regex)
• test/TestRegex.fs — 42 tests covering all major APIs
• src/Fable.Python.fsproj — include new source file
• test/Fable.Python.Test.fsproj — include new test file

Design notes

• Module is named Fable.Python.Regex (not Re) to avoid collision with F#'s own Regex from System.Text.RegularExpressions, and the binding value is re to mirror Python's import re.
• Match and Pattern are bound as [<Import(..., "re")>] classes with nativeOnly members — the same pattern as Queue, datetime, etc. Users never construct them directly.
• end is a reserved word in F# so is escaped as end in both the binding and tests.
• match is a reserved word in F# so is escaped as match where it appears as a method name on Pattern and as a module function. The IExports abstract match method uses backticks correctly.
• The Flags sub-module uses [<Literal>] integer constants so they can be used in ||| combinations.
• No existing signatures changed; this is a purely additive PR.
• Note: CHANGELOG.md is intentionally not updated per repository policy.

CI will validate the build and Python tests.

Note

🔒 Integrity filter blocked 10 items

The following items were blocked because they don't meet the GitHub integrity level.

• How does it generate the python source from AST? #5 list_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• Roadmap #15 list_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• Create Pyi parser #22 list_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• string format specifier '{i:X4}' not working #36 list_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• Support for Attributes? #48 list_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• Pandas binding #65 list_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• typeshed: generate bindings automatically ~ python glutinum? #115 list_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• auto pip installation of dependencies during compilation of scripts #117 list_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• allow TextIOWrapper to be enumerated #131 list_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• support for asynchronous context managers #134 list_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".

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