fix(ci): match the screenshot checkbox by wording, not emphasis (#6073)

The PR-description check folded the template's asterisks into the pattern,
so a ticked box written without them read as unchecked while rendering
identically on the PR page. `ready for review` was silently withheld and
the bot reported missing visual evidence even with screenshots attached,
with no way to tell from the rendered PR what was wrong.

The two attestations directly above it already anchor on the wording
alone. This one now does the same, accepting `**bold**`, `*italic*`,
`__underscores__` and plain text.

Fixes #6071

tests/test_pr_description_check.py

@@ -169,6 +169,20 @@ def test_ui_checkbox_without_media_still_needs_visual_evidence():
     assert not any(call["method"] == "setFailed" for call in calls)
 
 
+def test_ticked_screenshot_box_counts_without_the_template_bolding():
+    body = _body(
+        app_ran=True,
+        screenshot=True,
+        media="https://github.com/user-attachments/assets/example",
+    ).replace("**Screenshot or short clip**", "Screenshot or short clip")
+
+    calls = _run_checker(["static/js/example.js"], body)
+
+    assert _added_labels(calls) == {"ready for review"}
+    assert not _comment(calls)
+    assert not any(call["method"] == "setFailed" for call in calls)
+
+
 def test_explicit_not_run_is_honest_but_not_ready():
     calls = _run_checker(
         ["services/example.py"],