feat: reduce font-faces to single SBB variant

[jeripeierSBB]

BEGIN_COMMIT_OVERRIDE
feat: reduce font-faces to the single SBB variant (#2618)

BREAKING CHANGE: Replaced Roman, Bold, and Light font-face variants with the single SBB font. Using CSS font-weight property automatically selects the correct font family. Migration guide:

• Replace font-family: "SBBWeb Roman", ... with font-family: "SBB", ... and use font-weight: normal (potentially not necessary as normal is the default).
• Replace font-family: "SBBWeb Bold", ... with font-family: "SBB", ... and use font-weight: bold or CSS class sbb-text--bold.
• Replace font-family: "SBBWeb Light", ... with font-family: "SBB", ... and use font-weight: 300.
• Replace CSS variable --sbb-typo-type-face-sbb-roman with --sbb-typo-font-family and use font-weight: normal (potentially not necessary as normal is the default).
• Replace CSS variable --sbb-typo-type-face-sbb-bold with --sbb-typo-font-family and use font-weight: bold.
• Replace CSS variable --sbb-typo-type-face-sbb-light with --sbb-typo-font-family and use font-weight: 300.

END_COMMIT_OVERRIDE

Closes #2614

BREAKING CHANGE: replaced Roman, Bold, and Light font-face variants with the single "SBB" font.
Using CSS font-weight property automatically selects the correct font family.
Migration guide:

• Replace font-family: "SBBWeb Roman", ... with font-family: "SBB", ... and use font-weight: normal (potentially not necessary as normal is the default).
• Replace font-family: "SBBWeb Bold", ... with font-family: "SBB", ... and use font-weight: bold or CSS class sbb-text--bold.
• Replace font-family: "SBBWeb Light", ... with font-family: "SBB", ... and use font-weight: 300.
• Replace CSS variable --sbb-typo-type-face-sbb-roman with --sbb-typo-font-family and use font-weight: normal (potentially not necessary as normal is the default).
• Replace CSS variable --sbb-typo-type-face-sbb-bold with --sbb-typo-font-family and use font-weight: bold.
• Replace CSS variable --sbb-typo-type-face-sbb-light with --sbb-typo-font-family and use font-weight: 300.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.23%. Comparing base (e6397df) to head (66a54e0).
Report is 23 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2618      +/-   ##
==========================================
+ Coverage   93.18%   93.23%   +0.04%     
==========================================
  Files         316      316              
  Lines       25389    25346      -43     
  Branches     2063     2070       +7     
==========================================
- Hits        23660    23631      -29     
+ Misses       1696     1682      -14     
  Partials       33       33              

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[kyubisation]

LGTM 👍
Nice work! 😃