Use wrapping_add(1) in seqlock_begin_write for overflow consistency

[SaitejaKommi]

Summary

seqlock_begin_write increments the generation counter using normal integer addition, while seqlock_end_write already uses wrapping_add.

Location

apis/python/node/src/lib.rs

Current behavior

The write-begin path increments the generation counter using:

pre_write_gen + 1

The write-end path already uses:

wrapping_add(2)

This creates inconsistent overflow handling.

In debug builds, normal integer addition can panic on overflow, whereas wrapping_add preserves the intended wrapping semantics of the sequence counter.

Suggested fix

Replace

pre_write_gen + 1

with

pre_write_gen.wrapping_add(1)

to make both write paths use consistent overflow behavior.