fix(dev_snp): Support pipeline flows for SNP verification

[PeterFarber]

Summary

• Fix SNP verify to check M1 first (pipeline result), then fall back to M2 (direct call)
• Add fallback to raw message when report key not found in committed message
• Return proper error instead of crashing when report key is missing

Context

When using SNP verification in a pipeline flow like:

/~relay@1.0/call&relay-path=".../~snp@1.0/generate"/verify~snp@1.0

The relay result (containing the SNP report) is passed as M1, not M2. Previously, verify/3 only looked in M2, causing verification to fail with a function_clause error when json:decode received not_found.