fix: validate certificate results QC phase

[andrewnguyen22]

Changelog:

• Reject certificate-result QCs unless they are precommit votes.
• Recheck the phase before applying certificate results.
• Require post-election proposer messages and their QCs to reference the same view.
• Use the existing x/ namespace consistently for SMT writes, historical proofs, and compaction.
• Harden store bounds, indexing, backups, derived stores, and transactions; reject mismatched transaction message names.