swev-id: astropy__astropy-13453 Fix HTML writer formatting handling

[casey-brooks]

Summary

• ensure the HTML writer applies configured column formats before output
• preserve column formatting when expanding multidimensional cells
• add regression tests for numeric, masked, quantity/mixin, and raw HTML columns

Testing

• XDG_CONFIG_HOME=/workspace/.config LD_LIBRARY_PATH=/nix/store/wffgswxkp55xi14jy63rjsnfvl2qvmxy-gcc-14.3.0-lib/lib:$LD_LIBRARY_PATH /workspace/astropy/.venv/bin/python -m pytest --pyargs astropy.io.ascii.tests.test_html
• .venv/bin/isort astropy/io/ascii/html.py astropy/io/ascii/tests/test_html.py
• .venv/bin/pyupgrade --py38-plus astropy/io/ascii/html.py astropy/io/ascii/tests/test_html.py
• .venv/bin/flake8 --count --select E101,W191,E201,E202,W291,W292,W293,W391,E111,E112,E113,E30,E502,E722,E901,E902,E999,F822,F823 astropy/io/ascii/html.py astropy/io/ascii/tests/test_html.py

Fixes #72

[casey-brooks]

Local Validation

• XDG_CONFIG_HOME=/workspace/.config LD_LIBRARY_PATH=/nix/store/wffgswxkp55xi14jy63rjsnfvl2qvmxy-gcc-14.3.0-lib/lib:$LD_LIBRARY_PATH /workspace/astropy/.venv/bin/python -m pytest --pyargs astropy.io.ascii.tests.test_html
• .venv/bin/isort astropy/io/ascii/html.py astropy/io/ascii/tests/test_html.py
• .venv/bin/pyupgrade --py38-plus astropy/io/ascii/html.py astropy/io/ascii/tests/test_html.py
• .venv/bin/flake8 --count --select E101,W191,E201,E202,W291,W292,W293,W391,E111,E112,E113,E30,E502,E722,E901,E902,E999,F822,F823 astropy/io/ascii/html.py astropy/io/ascii/tests/test_html.py

[noa-lucent]

Looks great. Thanks!