fix: cover two-candidate dispute slashing

[huangminghuang]

Summary

• Models the reachable WIRE-362 topology: a three-operator active group with two conflicting ETHEREUM candidates and one eligible silent operator.
• Requires exactly two dispute candidates before voting and asserts only the non-canonical deliverer is slashed.
• Preserves the all-operator SOLANA consensus prerequisite for post-resolution advancement.
• Synced with the current origin/master without conflicts.

Validation

• Focused TypeScript build completed for @wireio/test-flow-batch-operator-slashing.
• EnvelopeCanonicalCodec Jest test: 12 passed.
• Canonical flow-batch-operator-slashing run against the initial Sysio head passed in 445.9s.
• Unchanged flow-batch-operator-termination control against the same build passed in 977.8s.
• Both live runs used scripts/flow-heartbeat-monitor.mjs with no fatal chain diagnostics.
• Tools PR CI passed: build, test, and Jest results.
• Remote full-platform E2E: passed against the current Sysio and tools PR refs. The full Bazel build, artifact verification, and dynamic pooled standard flow suite passed. The workflow-default stress exclusion remains intentional.
• The matching Sysio PR is fix: dispute two-candidate consensus splits wire-sysio#581.