scripts/validate-config-examples.mjs validates complete Mergify
configurations against the JSON schema, which sees a condition as a string and
so cannot tell a working one from a dead one. That left a whole class of broken
example invisible: - files ~= "^ui/" is valid YAML and a valid schema value,
but the quotes are part of the pattern, because YAML only strips quotes that
open a scalar and Mergify hands a ~= or *= value to the pattern engine
verbatim. The compiled pattern expects a literal double quote before a
start-of-string anchor and matches nothing, so the rule silently does nothing.
Two recipes in the merge-protections pages had it.

The check now also looks at every YAML block, not only the ones classified as
complete configurations, since most conditions in the docs live in fragments
showing a single rule. It flags a list item whose scalar is unquoted and whose
~= or *= value is wrapped in a matching pair of quotes. A condition the
author quoted as a whole is left alone, as is a pattern that merely contains a
quote, both covered by tests.

Open question: whether this belongs in the schema validator at all rather than
in a lint of its own. It lives here because this script already extracts and
classifies every YAML block in the corpus, and a second script would duplicate
that half; the cost is that a failure now reports as a config-example problem
when it is really a condition-language one, which is why the failure message
spells out the fix.