fix(scripts): force UTF-8 stdout in design_system.py on Windows (#112)

[ia-abatista]

What & why

On a non-UTF-8 Windows console (cp1252/gbk), running design_system.py as a CLI crashes with UnicodeEncodeError -- the same class of failure reported in #112 for search.py. The script prints box-drawing characters, check marks, and block swatches, but unlike search.py it never reconfigured stdout.

Note: the search.py instance from #112 is already fixed on main (it wraps stdout/stderr in a UTF-8 TextIOWrapper at lines 23-27). This PR covers the remaining design_system.py gap.

Change

Mirror search.py's wrapper in design_system.py:

if sys.stdout.encoding and sys.stdout.encoding.lower() != 'utf-8':
    sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-8')
if sys.stderr.encoding and sys.stderr.encoding.lower() != 'utf-8':
    sys.stderr = io.TextIOWrapper(sys.stderr.buffer, encoding='utf-8')

Applied to the source of truth (src/ui-ux-pro-max/scripts/) and the synced cli/assets/ copy. The check is idempotent, so it is a no-op when search.py imports design_system (stdout is already UTF-8 by then).

Verification

• PYTHONIOENCODING=cp1252 python design_system.py "saas dashboard" --format ascii -> exit 0, no UnicodeEncodeError, still emits the box/swatch output (50 lines with non-ASCII).
• npm run check:assets passes (both copies in sync).

Related to #112.

[ia-abatista]

@mrgoonie more cleanup

[mrgoonie]

Maintainer review: approved. This is a narrow fix for the remaining Windows non-UTF-8 console path in design_system.py, mirrors the existing search.py stdout/stderr UTF-8 wrapper, and keeps source-of-truth plus packaged cli/assets copies in sync. Verified locally: npm run check:assets passes, and PYTHONIOENCODING=cp1252 python3 src/ui-ux-pro-max/scripts/design_system.py "saas dashboard" exits successfully while emitting the box/swatch output instead of raising UnicodeEncodeError. Duplicate/prior-work search only found this PR for the design_system.py-specific gap; related #112 search.py behavior is already fixed on main.