Remove vertical ascent compensation and update test references

[JimBobSquarePants]

• I have written a descriptive pull-request title
• I have verified that there are no overlapping pull-requests open
• I have verified that I am following matches the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
• I have provided test coverage for my change (where applicable)

Description

This pull request refines the vertical glyph layout logic in TextLayout.cs by removing first-line ascent compensation for vertical and vertical-mixed text flows. This change prevents unwanted extra spacing before the first glyph, ensuring more visually consistent vertical text rendering. Additionally, several reference images for composed character vertical rendering tests have been updated to reflect the improved layout.

Vertical layout logic improvements:

• Removed first-line Y ascent compensation in both LayoutLineVertical and LayoutLineVerticalMixed, restricting baseline adjustment to X-origin block alignment only. This prevents unnecessary leading space above the first glyph in vertical text columns. [1] [2]
• Updated glyph advance calculations to exclude extra ascent, ensuring advances are based solely on the actual glyph metrics. [1] [2] [3] [4] [5]

Test reference updates:

• Updated output images for composed character vertical rendering tests to match the new, corrected layout behavior. [1] [2] [3] [4]### Prerequisites

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83%. Comparing base (8d3c065) to head (933f4c1).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #505   +/-   ##
=====================================
  Coverage     83%     83%           
=====================================
  Files        274     274           
  Lines      19184   19171   -13     
  Branches    2719    2717    -2     
=====================================
- Hits       16081   16071   -10     
+ Misses      2426    2424    -2     
+ Partials     677     676    -1     

Flag	Coverage Δ
unittests	83% <100%> (+<1%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.