[guido4096]

The host persistence tests used a fabricated stat layout and stubs that always failed stat() and remove(). This prevented the tests from exercising real filesystem behavior. The FreeRTOS mock also included C++ standard headers inside extern "C", making compilation depend on include order.

Use the host's actual sys/stat.h and filesystem functions, and move the standard headers outside the C linkage block. This changes host-test infrastructure only; firmware behavior is unchanged.

Validation

• 169 host tests passed on this standalone branch (macOS, POSIX enabled, original pinned eBUS revision f730dce).
• Whitespace checks passed. CI and a fresh firmware build for this isolated branch are pending.

The standalone run uses the checked-in mock fixes from this PR. No firmware source is changed.

Related runtime fixes

Part 1/5 of the single-commit replacements for #430, split at the maintainer's request. Every PR targets master directly and contains only its corresponding change.

Part	Scope	PR / branch
1/5	Correct host-test mocks	#431
2/5	Bound Logs page retention	#432
3/5	Schedule diagnostics by elapsed time	#433
4/5	Protect string-pool IDs and concurrent access	#434
5/5	Buffer HTTP streams and stop after send failures	#435

Suggested merge order: the host-test mock fix first, then the other four changes independently. The five patches together reconstruct the exact tracked file tree of #430.

Source commit in #430: bf972bc.