fix(satp-hermes): add missing await to async DB writes in Stage 3 asset operations

[mn-ram]

Summary

• Add missing await to 12 fire-and-forget persistLogEntry() and storeProof() calls in mintAsset(), burnAsset(), and assignAsset() methods
• Prevents unhandled promise rejections that crash the SATP gateway (exit code 255)
• Eliminates silent loss of blockchain transaction proofs needed for crash recovery

Fixes #1

Problem

In Stage 3 services, the asset operation methods (mintAsset, burnAsset, assignAsset) call this.dbLogger.persistLogEntry() and this.dbLogger.storeProof() without await. Both are async methods that write to local + remote databases.

This is inconsistent — every other method in the same files correctly awaits these calls.

Without await:

1. DB write errors become unhandled promise rejections → process crash
2. Proofs may not persist before the method returns → silent data loss
3. Crash recovery can't find proofs → re-executes operations → duplicate blockchain transactions

Changes

File	Method	Lines Fixed
stage3-server-service.ts	mintAsset()	818, 827, 870, 880
stage3-server-service.ts	assignAsset()	911, 921, 965, 977
stage3-client-service.ts	burnAsset()	782, 792, 835, 844

Test plan

• Verify existing SATP integration tests still pass
• Verify Stage 3 asset operations correctly await DB writes
• Confirm no remaining unawaited dbLogger calls in affected files

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