pack-objects(check_pack_inflate()): use size_t instead of unsigned long

`write_reuse_object()` learned to track its packed-object size as `size_t` in 606c192380 (odb, packfile: use size_t for streaming object sizes, 2026-05-08), but the comparison sink it feeds, `check_pack_inflate()`, still takes the expected decompressed size as `unsigned long`. The call site bridges the mismatch with `cast_size_t_to_ulong()`, which on Windows turns a >4 GiB object into an immediate die(). That function only uses `expect` once: as the right-hand side of a `stream.total_out == expect` equality test against zlib's counter. zlib's own `total_out` counter is `uLong` and is therefore still 32-bit-bound on Windows. Widening `expect` to `size_t` cannot fix that, but it is a strict improvement nonetheless: instead of dying outright, an oversized object now simply makes the equality fail and lets `write_reuse_object()` fall back to `write_no_reuse_object()`, which decompresses and re-deflates the content (and which the larger pack-objects widening series targets separately). Drop the `cast_size_t_to_ulong()` shim at the call site now that the receiving parameter speaks the same type as `entry_size`. Assisted-by: Opus 4.7 Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>