🐛 fix(ci): strip ordering markers from changelog section headers

[sodre]

Summary

• git-cliff section group names in cliff.toml embed <!-- N --> ordering markers (e.g. <!-- 4 -->Refactoring) to control section order. The changelog body template rendered the raw group name, leaking the marker into rendered headers — visible as ### <!-- 4 -->Refactoring in the v0.10.2 changelog and GitHub Release notes.
• Fix: add the canonical striptags | trim filters to the group header in the body template (### {{ group | striptags | trim | upper_first }}). This is display-only; section ordering is unchanged.

Test plan

• Rendered the full changelog locally with uvx git-cliff --config cliff.toml — all 12 section headers (Features, Bug Fixes, Refactoring, etc.) render cleanly with zero ### <!-- leaks
• Confirmed the v0.10.2 section renders as ### Refactoring

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 29.14%. Comparing base (4f7cd02) to head (b3800e4).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

❗ There is a different number of reports uploaded between BASE (4f7cd02) and HEAD (b3800e4). Click for more details.

HEAD has 3 uploads less than BASE

Flag	BASE (4f7cd02)	HEAD (b3800e4)
unit	1	0
e2e	1	0
integration	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #427       +/-   ##
===========================================
- Coverage   92.39%   29.14%   -63.26%     
===========================================
  Files          37       37               
  Lines        7854     7854               
===========================================
- Hits         7257     2289     -4968     
- Misses        597     5565     +4968     

Flag	Coverage Δ
doctest	29.14% <ø> (ø)
e2e	?
integration	?
unit	?

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