Fix report order for unfinished nested sections

Description

Nested SKIP, fatal assertions, and unexpected exceptions defer section endings until stack unwinding completes. The section information is queued inner-first, but the reverse traversal emits outer endings first. CumulativeReporterBase assigns those statistics to the current inner node, corrupting section names and hierarchy.

Process the deferred endings in enqueue order. A real custom cumulative reporter checks balanced start/end names and the resulting tree paths for skip, fatal failure, unexpected exception, and normal completion. The first three fail before the fix; all four pass afterward.

The four updated JUnit/SonarQube approval files now show the actual nested paths and remove spurious parent nodes. Amalgamated files were regenerated locally for testing and are excluded from this commit.

Validation on Linux with GCC 13.3: complete all-tests build and all 160 CTest checks pass, including examples, extra tests, configuration/helper checks, signals, and approval outputs. Changed source and the new fixture also pass C++14 syntax checks. The new fixture passes clang-format.

Prepared with OpenAI Codex assistance; the reported failure was reproduced and the submitted source was tested locally.

GitHub Issues

Closes #2928.