Add SDC fault confidence levels and reporting

[wangxumarshall]

Motivation

• Provide a confidence classification for SDC (Silent Data Corruption) reports so detections can be distinguished by evidence strength and acted on differently.
• Allow callers to supply a confidence level when logging faults so different detection mechanisms (checksum vs statistical checks) are recorded with appropriate severity.
• Extend the aggregated report to present per-fault confidence and a confidence-level summary to aid node triage and automated tooling.

Description

• Add a new enum HPL_T_SDC_CONFIDENCE with HPL_SDC_CONFIRMED, HPL_SDC_SUSPECTED, HPL_SDC_WARNING and a confidence field to HPL_T_SDC_FAULT in hpl/include/hpl_sdc.h.
• Introduce HPL_sdc_log_fault_ex(...) (accepts confidence) and keep HPL_sdc_log_fault(...) as a wrapper that logs with HPL_SDC_SUSPECTED; update prototypes accordingly.
• Update hpl/src/sdc/HPL_sdc_report.c to record, gather and print confidence per fault, add HPL_sdc_confidence_str(...), and include a summary counts block for confidence levels in the aggregated report.
• Add a classifier HPL_sdc_classify_panel_entry(...) in hpl/src/sdc/HPL_sdc_verify.c that maps NaN/Inf to CONFIRMED and finite range overflow to SUSPECTED.
• Update call sites so detections are logged with an appropriate confidence mapping: broadcast raw checksum mismatch -> CONFIRMED; non-NaN finite/overflow panel entry / floating checksum anomalies -> SUSPECTED (via classifier); panel NaN/Inf -> CONFIRMED (via classifier); panel range overflow -> SUSPECTED; back-solve NaN/Inf -> CONFIRMED; back-solve 6-sigma outliers -> WARNING.

Testing

• Ran git diff --check to validate whitespace and simple issues and fixed end-of-line normalization; this passed after fixes.
• Per-file syntax checks were performed with gcc -DHPL_SDC_CHECK -DAdd__ -DF77_INTEGER=int -DStringSunStyle -I/tmp/hpl_fake_mpi -Ihpl/include -Ihpl/include/WSL_SDC_CHECK_ONLY -fsyntax-only <file> for all modified C files, using a minimal fake mpi.h (typedefs for the MPI symbols used); these syntax-only checks succeeded.
• Attempted a full build with make -C hpl arch=WSL_SDC_CHECK_ONLY, but the build failed in this environment due to platform-specific Make.inc symlink resolution and missing platform Make.inc (environmental issue), so a full compile/link was not completed here.

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Codex Task