fix: avoid SIGFPE on x86_64 for signed integer division overflow

[kim-em]

This PR fixes a SIGFPE crash on x86_64 when evaluating INT_MIN / -1 or INT_MIN % -1 for signed integer types.

On x86_64, the idiv instruction traps when the quotient overflows the destination register. For signed integers, INT_MIN / -1 produces a result that overflows (e.g., -2147483648 / -1 = 2147483648 which doesn't fit in Int32). ARM64's sdiv instruction wraps instead of trapping.

The fix:

• For Int8/Int16/Int32: widen to the next larger type before dividing/modding, then truncate back
• For Int64: explicitly check for the overflow case and return the wrapped result

Fixes #11612

🤖 Prepared with Claude Code

[leanprover-community-bot]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 3bd1dd633f29de1dd0ea0e23833da7710bdb1c25 --onto 19e1fe55f33a8aadc4243da32828b70a4b4677cc. You can force Mathlib CI using the force-mathlib-ci label. (2025-12-12 00:54:52)

[leanprover-bot]

Reference manual CI status:

• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase 3bd1dd633f29de1dd0ea0e23833da7710bdb1c25 --onto eee58f4506d28a14c9a171165f999445a0663d93. You can force reference manual CI using the force-manual-ci label. (2025-12-12 00:54:53)

[sgraf812]

(LGTM!)