* scripts: make check_redundant_patches.py executable
The redundant-test-patches pre-commit hook uses `language: script`, which
requires the executable bit, and fails on every commit touching Lib/test.
Assisted-by: Claude:claude-sonnet-5-5
* csv: support non-ASCII Unicode dialect characters
Store delimiter, quotechar and escapechar as `char` instead of `u8`, and
run the reader state machine and the writer over code points, so that a
single non-ASCII character such as `€` is accepted like in CPython. The
field size limit is now counted in characters rather than bytes.
Fixes#8408
Assisted-by: Claude:claude-sonnet-5-5
Mathieu Dupuy