The modal HTML was assembled via raw f-string concatenation in
``delete_preview``. Move it to a dedicated Jinja2 partial
(``chat/templates/_delete_impact_modal.html``) and render via
``TEMPLATES.TemplateResponse``. Jinja2 autoescape now handles HTML
safety automatically — the explicit ``html.escape()`` calls added in
T110.2 (and the ``import html``) become redundant and are removed in
this commit.
Net behavioural change: attribute quoting style flips from single to
double quotes (Jinja default) — the existing T98.4 substring-based
assertions are unaffected, and the new T110.3 test pins the
double-quoted shape so future regressions surface.
Test: tests/test_drawer_phase4.py::test_delete_impact_modal_uses_jinja_partial.
Joseph Doherty
5d5c888acf