Compare only W0 bank hashes in BTrace

[daiyongyuan]

Summary

• Change BTrace records and RTL DPI callbacks to carry only the W0 logical bank ID and hash.
• Emit BEMU records only for eligible write-bank instructions, retaining instruction IDs and multi-group hash combination.
• Compare by (hart_id, inst_id) and W0; reject legacy three-slot records and duplicate offline records.

Verification

• cargo test --offline -p bebop-bank-hash (4 tests passed)
• cargo check --offline -p bebop-rtl-trace
• Pebble generated BEMU manifest: cargo check --offline
• cargo fmt --all --check

This is the Bebop half of the W0-only bank-hash diff change in DangoSys/buckyball#125. End-to-end RTL/BEMU workload simulation was not run in this change.