Commit 7: Add Consistency.ql regression guard

New cpp/ql/test/library-tests/regex/Consistency.ql selects, for each
corpus RegExp, characters that failedToParse. The empty
Consistency.expected asserts that no corpus regex has any unparsed
character, mirroring PR #22200's Consistency test as the primary
regression guard for the parser.

Bundle: github/codeql-action codeql-bundle-v2.26.1 (CodeQL CLI 2.26.1).

Author: Copilot

cpp/ql/test/library-tests/regex/Consistency.expected

@@ -0,0 +1,11 @@
+/**
+ * Regression guard: every corpus regex must parse without leaving any
+ * character unaccounted for. Expected output is empty.
+ */
+
+import cpp
+import semmle.code.cpp.regex.internal.ParseRegExp
+
+from RegExp re, int i
+where re.failedToParse(i)
+select re, i, re.getChar(i)