Align integer conversion and byte controls - #9702

Summary

Align integer conversions and byte controls with CPython 3.15 in 427 changed production Rust lines across five files.

• Retain derived argument binding for int.from_bytes and int.to_bytes, then perform length, byteorder type, signed truth and byteorder value checks in the native order. Keep raw controls alive through conversion and result construction, and share reverse-parameter cleanup on success and body-level errors.
• Use the exact bytes fast path, SIMPLE buffer acquisition and existing bytes/iterable fallback in from_bytes. Release temporary exports and returned bytes before integer-subclass construction.
• Share literal parsing and canonical bytes diagnostics between implicit and explicit-base integer construction. Preserve string repr callbacks, truncate repr by code points, and retain surrogate text.
• Share __int__/__index__ result checks, normalize deprecated __int__ subclass results to exact integers, and propagate warning errors.
• Reuse the same strict ssize helper as Align native sequence iterator state and lifecycle #9701 and lossless warning helper as Preserve Unicode in shared qualified type names #9700. These are identical shared helpers, not new per-method parsers.

No Python, Lib, tests, expected-failure markers or workflow changes.

Reference and validation

Compared with CPython commit d220409a13b77de7a6c30abe16ea90db01528edc: integer implementation, generated argument conversions, and numeric protocols.

• 332 bounded reference assertions plus 11 conversion/lifetime controls and nine independent destruction-order cases. These are CPython/source checks, not RustPython runtime execution.
• Independent source review corrected early raw-argument release and declaration-order cleanup before publication. Separate source-composition review preserves numeric normalization, lossless qualified names and exactly one shared helper with Align numeric conversion and rounding boundaries #9697, Preserve Unicode in shared qualified type names #9700 and Align native sequence iterator state and lifecycle #9701. Textual conflicts require retaining both PyObject/PyComplex imports and the shared integer result checks; the combined peer composition was not compiled.
• Focused host-env/VM/stdlib threading cargo check, normal all-targets Clippy, formatting, diff checks and ordinary commit hooks passed. Four Clippy diagnostics match unchanged main: one POSIX needless-collect and three ElementTree lints. No warning suppression; strict -D warnings remains blocked by that baseline.

Native RustPython execution, full workspace/C-API runtime suites and cross-platform tests were not run. Hosted CI remains required.

Remaining boundaries

• Cleanup follows canonical parameter order. Arbitrarily reordered keyword evaluation and errors during the shared binder itself retain existing binder-level lifetime differences; no full call-stack finalizer parity is claimed.
• Surrogate-qualified type names depend on the underlying helper migration in Preserve Unicode in shared qualified type names #9700. This PR's formatting accepts both current and migrated helper types.
• Existing int.from_bytes('text') fallback wording and generic bytes() collection distinctions remain outside scope. Cross-thread scheduling and unrelated allocation timing are unchanged.

AI-assisted implementation and independent review using OpenAI Codex; model version is not exposed.