Extend the source-safety self-test to prove fprintf(stdout, ...) is rejected in MCP/pipeline code, matching the existing protocol-output guard.
Reuse store.c's heap_strdup helper for neighbor-name and LIKE-hint allocations instead of direct strdup calls. This keeps ownership behavior unchanged while reducing allocator-wrapper drift in touched store paths.
Validation: make -j8 -f Makefile.cbm build/c/test-runner; CBM_ONLY_SUITE=store_search ./build/c/test-runner; CBM_ONLY_SUITE=mcp ./build/c/test-runner; bash scripts/check-source-safety.sh; bash scripts/test-source-safety.sh; git diff --check.
Signed-off-by: Andrew Hundt <ATHundt@gmail.com>