* sqlite3: fix Blob.__setitem__ value range validation
Previously, assigning an out-of-range integer (negative or > 255) or an
integer too large for i64 (e.g. 2**65) to a Blob index raised OverflowError
instead of ValueError.
Mirror CPython's ass_subscript_index logic:
- Convert the value via to_i64(), treating any overflow as -1
- Validate the result is in [0, 255], raising ValueError("byte must be in range(0, 256)") otherwise
- Separate deletion error messages: "item deletion" for index, "slice deletion" for slice
* sqlite3: fix Blob.__setitem__ negative-step slice write
In the step != 1 branch of Blob.ass_subscript, the loop used
i_in_temp += step as usize
where step is isize. For negative steps (e.g. step = -2),
(-2isize) as usize = 18446744073709551614
causing an out-of-bounds panic whenever slice_len >= 2.
Fix: use SaturatedSliceIter (already used by the read path) to iterate
over the correct absolute blob indices, then map each index back to a
temp buffer offset via abs_idx - range_start.
Also fix a Clippy lint: replace
val < 0 || val > 255
with the idiomatic
!(0..=255).contains(&val)
Add a regression test in extra_tests/snippets/stdlib_sqlite.py that
exercises blob[9:0:-2] (negative step, slice_len=5).
* fix: guard blob negative-step snippet from CPython 3.11 bug
* style: add blank line after import sys in stdlib_sqlite snippet (ruff)
* Update extra_tests/snippets/stdlib_sqlite.py
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Co-authored-by: Jeong, YunWon <69878+youknowone@users.noreply.github.com>
