fix: scope warning suppression and keep consumer macros clean

[sunxfancy]

Recent EVEngine CI emitted 4,306 unknown-warning-group diagnostics per run from zeroerr, plus MSVC macro-shadowing and CRT deprecation noise. Check Clang warning-group support before suppressing it and balance the variadic diagnostic push/pop so suppression cannot leak into consumer code.

Rename the context macro's internal loop variable, scope CRT deprecation suppression to the logging implementation, and remove an unused callback parameter name. Fix GCC-invalid pragma placement in fuzz-test and subcase macros. Regenerate the single header and add compiler regressions, including expected failures that ensure consumer diagnostics remain enabled. Enable the existing workflow for dev PRs.

Validation:

• zeroerr CTest suite passed on MSVC, GCC and Clang: zero failures (the suite retains its two skipped cases).
• Warning-hygiene probes passed on all three compilers, including split headers, single-header implementation, macro declarations, and consumer deprecation diagnostics. Clang diagnostic restoration checks passed.
• The new regression probe fails against the original dev revision on macro variable shadowing.
• EVEngine 6443348d0eed: final Windows Debug build with the native test plugin, followed by all 3,902 default process-isolated CTest entries passing in 252 seconds. The first run exposed missing local test prerequisites; both were supplied and the entire suite rerun successfully. Local prebuilt dependencies were reused after verifying identical source Git trees.

This does not suppress the serialization memory-operation warnings or warnings that expose unimplemented serialization/logging behavior.